***SLEEP - GENERAL
Nature 427, 352 - 355 (22 January 2004);
Sleep inspires insight
ULLRICH WAGNER, STEFFEN GAIS, HILDE HAIDER, ROLF VERLEGER & JAN BORN
wagner@kfg.uni-luebeck.de
or J.B.born@kfg.uni-luebeck.de
Insight
denotes a mental restructuring that leads to a sudden gain of explicit
knowledge allowing qualitatively changed behaviour. Anecdotal reports on
scientific discovery suggest that pivotal insights can be gained through sleep.
Sleep consolidates recent memories and, concomitantly, could allow insight by
changing their representational structure. Here we show a facilitating role
of sleep in a process of insight. Subjects performed a cognitive task requiring
the learning of stimulus-response sequences, in which they improved gradually
by increasing response speed across task blocks. However, they could also
improve abruptly after gaining insight into a hidden abstract rule underlying
all sequences. Initial training establishing a task representation was followed
by 8 h of nocturnal sleep, nocturnal wakefulness, or daytime wakefulness. At
subsequent retesting, more than twice as many subjects gained insight into the
hidden rule after sleep as after wakefulness, regardless of time of day. Sleep
did not enhance insight in the absence of initial training. A characteristic
antecedent of sleep-related insight was revealed in a slowing of reaction times
across sleep. We conclude that sleep, by restructuring new memory
representations, facilitates extraction of explicit knowledge and insightful
behaviour.
Public Library of Science Biology (online)
Volume 2 | Issue 1 | January 2004
Long-Lasting Novelty-Induced Neuronal Reverberation
during Slow-Wave Sleep in Multiple Forebrain Areas
Sidarta Ribeiro1, Damien Gervasoni, Ernesto S. Soares, Yi
Zhou1, Shih-Chieh Lin, Janaina Pantoja, Michael Lavine, Miguel A. L. Nicolelis
`The
discovery of experience-dependent brain reactivation during both slow-wave (SW)
and rapid eye-movement (REM) sleep led to the notion that the consolidation of
recently acquired memory traces requires neural replay during sleep. To date,
however, several observations continue to undermine this hypothesis. To address
some of these objections, we investigated the effects of a transient novel
experience on the long-term evolution of ongoing neuronal activity in the rat
forebrain. We observed that spatiotemporal patterns of neuronal ensemble
activity originally produced by the tactile exploration of novel objects
recurred for up to 48 h in the cerebral cortex, hippocampus, putamen, and
thalamus. This novelty-induced recurrence was characterized by low but
significant correlations values. Nearly identical results were found for
neuronal activity sampled when animals were moving between objects without
touching them. In contrast, negligible recurrence was observed for neuronal
patterns obtained when animals explored a familiar environment. While the
reverberation of past patterns of neuronal activity was strongest during SW
sleep, waking was correlated with a decrease of neuronal reverberation. REM
sleep showed more variable results across animals. In contrast with data from hippocampal place cells, we found no evidence of time
compression or expansion of neuronal reverberation in any of the sampled
forebrain areas. Our results indicate that persistent experience-dependent
neuronal reverberation is a general property of multiple forebrain structures.
It does not consist of an exact replay of previous activity, but instead it
defines a mild and consistent bias towards salient neural ensemble firing
patterns. These results are compatible with a slow and progressive process of
memory consolidation, reflecting novelty-related neuronal ensemble
relationships that seem to be context- rather than stimulus-specific. Based on
our current and previous results, we propose that the two major phases of
sleep play distinct and complementary roles in memory consolidation: pretranscriptional recall during SW sleep and
transcriptional storage during REM sleep.
J Neuropsychiatry Clin Neurosci 16:19-28, February 2004
Acupuncture Increases Nocturnal Melatonin Secretion and
Reduces Insomnia and Anxiety: A Preliminary Report
D. Warren Spence, M.A., Leonid Kayumov,
Ph.D., DABSM, Adam Chen, Ph.D., Alan Lowe, M.D., Umesh
Jain, M.D., Martin A. Katzman, M.D., Jianhua Shen, M.D., Boris
Perelman, Ph.D. and Colin M. Shapiro, MBBCh, Ph.D.,
FRCP(C); lkayumov@uhnres.utoronto.ca (E-mail).
The
response to acupuncture of 18 anxious adult subjects who complained of insomnia
was assessed in an open prepost clinical trial study.
Five weeks of acupuncture treatment was associated with a significant (p =
0.002) nocturnal increase in endogenous melatonin secretion (as measured in
urine) and significant improvements in polysomnographic
measures of sleep onset latency (p = 0.003), arousal index (p = 0.001), total
sleep time (p = 0.001), and sleep efficiency (p = 0.002). Significant
reductions in state (p = 0.049) and trait (p = 0.004) anxiety scores were also
found. These objective findings are consistent with clinical reports of
acupuncture's relaxant effects. Acupuncture treatment may be of value for some
categories of anxious patients with insomnia.
Sleep Med. 2003 Jan;4(1):57-62.
A meta-analysis of sleep changes associated with
placebo in hypnotic clinical trials.
OBJECTIVES:
The effects associated with placebo (EAP) have been incompletely described in
clinical trials of insomnia treatment. We conducted a meta-analysis of insomnia
medication trials for the purpose of estimating the magnitude of sleep EAP.
METHOD: We reviewed Medline for 1966 through 2000 for the meta-analysis. The
subject heading of insomnia restricted to the subheading of drug therapy was
crossed against the results of a search on the subjects heading placebo and
text word placebo. We selected only papers that examined primary insomnia,
incorporating both placebo and active medication therapies in a randomized,
double-blind, parallel-group design. We required that results be reported for
1, 2, 3, or 4 weeks of treatment, and that outcomes be reported in
hours/minutes. RESULTS: Five papers satisfied our requirements for eligibility,
comprising 213 patients receiving placebo for a 2-week interval. Subjective
sleep latency demonstrated a significant reduction (mean+/-S.E.) of 13.1+/-2.0
min (95% confidence interval (CI) 9.2, 17.0) for the placebo group after
combining the data across studies. Subjective total sleep time demonstrated a
significant increase of 13.5+/-5.4 min (95% CI 2.9, 24.0). Polysomnographic
(PSG) sleep latency demonstrated a non-significant reduction of 2.5+/-4.3 min
(95% CI -5.9, 10.9). CONCLUSIONS: The confirmation of EAP in insomnia clinical
trials argues for the retention of a placebo control in future insomnia
clinical trials.
Am J Psychiatry. 2002 Jan;159(1):5-11.
Comparative meta-analysis of pharmacotherapy and
behavior therapy for persistent insomnia.
msmith62@jhmi.edu
OBJECTIVE:
Although four meta-analytic reviews support the efficacy of pharmacotherapy and
behavior therapy for the treatment of insomnia, no meta-analysis has evaluated
whether these treatment modalities yield comparable outcomes during acute
treatment. The authors conducted a quantitative review of the literature on the
outcome of the two treatments to compare the short-term efficacy of pharmacotherapy
and behavioral therapy in primary insomnia. METHOD: They identified studies
from 1966 through 2000 using MEDLINE, psycINFO, and
bibliographies. Investigations were limited to studies using prospective
measures and within-subject designs to assess the efficacy of benzodiazepines
or benzodiazepine receptor agonists or behavioral treatments for primary
insomnia. Benzodiazepine receptor agonists included zolpidem,
zopiclone, and zaleplon.
Behavioral treatments included stimulus control and sleep restriction
therapies. Twenty-one studies summarizing outcomes for 470 subjects met
inclusion criteria. RESULTS: Weighted effect sizes for subjective measures of
sleep latency, number of awakenings, wake time after sleep onset, total sleep
time, and sleep quality before and after treatment were moderate to large.
There were no differences in magnitude between pharmacological and behavioral
treatments in any measures except latency to sleep onset. Behavior therapy
resulted in a greater reduction in sleep latency than pharmacotherapy. CONCLUSIONS:
Overall, behavior therapy and pharmacotherapy produce similar short-term
treatment outcomes in primary insomnia
SLEEP DISORDERED
BREATHING (e.g., Apnea) AND COGNITION
Aloia MS, Ilniczky
N, Di Dio P, Perlis ML, Greenblatt DW, Giles
DE. mark_aloia@brown.edu
Neuropsychological changes and treatment compliance in
older adults with sleep apnea.
J Psychosom Res. 2003
Jan;54(1):71-6.
INTRODUCTION:
Apnea is a common disorder in older adults and has been shown to affect cognition.
Some studies suggest that treatment for apnea improves certain cognitive
deficits, but few studies have examined the relationship between compliance and
cognitive improvement. We designed a study to answer the following questions
about sleep apnea, cognition and treatment in older adults: (1) Which
neuropsychological (NP) variables are differentially associated with measures
of sleep fragmentation and oxygen desaturation? (2)
Does compliant use of CPAP provide a cognitive advantage over noncompliant use?
(3) Does NP performance at baseline predict compliance at 3 months? METHOD:
Twelve participants were recruited for the study. All had polysomnographically
defined sleep apnea with an RDI of 10 or greater. All were also at least 55
years of age, had no other diagnosable sleep disorder and had no previous
treatment for sleep apnea syndrome (SAS). Participants were administered a full
NP battery before and 3 months after treatment with CPAP. RDI at baseline was
associated with delayed verbal recall, while oxygen desaturation
was associated with both delayed recall and constructional abilities. Compliant
use of CPAP at 3 months was associated with greater improvements in attention,
psychomotor speed, executive functioning and nonverbal delayed recall. Finally,
attention measures predicted compliance at 3 months suggesting that those who
were least vigilant at baseline were more likely to comply with treatment.
DISCUSSION: Results are discussed in terms of the relevance to targeting
special populations for compliance interventions, the ways that treatment may
specifically affect older adults and the possible dose-response relationship of
CPAP.
Aldrich, M.S.
(1999). Sleep Medicine, NY:
Aguirre M, Broughton R, Struss
D. Does memory impairment exist in narcolepsy-cataplexy? J Clin
Exp Neuropsychol 1985;
American Thoracic Society. Sleep apnea, sleepiness, and
driving risk. Am J Respir Crit
Care Med 1994;150:1463-1473.
Andreou G, Galanopoulou
C, Gourgoulianis K, Karapetsas
A, Molyvdas P.
Cognitive status in Down syndrome individuals with
sleep disordered breathing deficits (SDB).
Brain Cogn. 2002 Oct;50(1):145-9.
Twelve
subjects with Down syndrome underwent polysomnographic
studies during night sleep and performed the Mini-Mental state test and the
Raven Progressive Matrices (RPM), sets A, B, and B(1). Sleep-disordered
breathing (SDB) deficits were observed in Down syndrome individuals and their
Mini-Mental and RPM scores were extremely low. Regression analysis of the
results revealed that the number of apneas per hour was related with the
results of the RPM, set A, which were also related with the orientation of
Mini-Mental test, indicating that the more apneas an individual has the more
difficulties he has in the kind of visuoperceptual
skills, including orientation, associated with normal right hemisphere
functioning, which are tested by set A of the RPM.
Archbold KH, Giordani
B, Ruzicka DL, Chervin
RD. archbold@u.washington.edu
Cognitive executive dysfunction in children with mild
sleep-disordered breathing.
Biol Res
Nurs. 2004 Jan;5(3):168-76.
In
children, moderate or severe sleep-disordered breathing (SDB) may impair
cognitive executive functions (EFs), including
working memory, attention, and mental flexibility. The main objective of this
study was to assess EFs in children with mild levels
of SDB. Subjects for this descriptive study were 12 children (5 girls, 7 boys)
aged 8.0 to 11.9 years (M = 9.0 +/- 0.85) participating in an ongoing study of
the effects of adenotonsillectomy on behavior. Each
subject had a nocturnal polysomnogram (PSG) and a
multiple sleep latency test (MSLT). Mild SDB was considered present if the
child's apnea/hypopnea index (AHI) was > or = 1
and < 10. Between MSLT nap attempts, each child completed standardized tests
of EFs. The sample showed significant impairment of
sustained attention and vigilance on a computerized continuous performance
test. Children with low mental flexibility scores on the Children's Category
Test (CCT) spent more time in stage 1 sleep (12.2% v. 9.5%, P = 0.028 on PSG)
and showed a marginally higher arousal index (9.7 v. 6.5, P = 0.06 on PSG) than
children with average or above-average CCT scores. AHI accounted for a
significant proportion of the variance in CCT scores when 1 outlier was removed
(N = 11, Rsq = 0.67, P = 0.002). Mild levels of
SDB and associated sleep architecture disruptions may be associated with
impairment of EFs in children.
Bearpark H, Grunstein
R, Touyz S, Channon L,
Sullivan C. Cognitive and psychological dysfunction in sleep apnea before and
after treatment with CPAP. Sleep Res 1987;16:303.
Beullens J.
[Sleep and intellectual functioning in the elderly: the
role of sleep quality and apnea--literature survey] [Article in Dutch]
Tijdschr Geron
In both
relatively healthy and in demented elderly people mental abilities and sleep
quality decrease in becoming older and nocturnal respiratory disturbance
increases. Perhaps there is an association between sleep and cognition. The
hypothesis that specific sleep phenomena are necessary to assure an adequate
level of cognitive functioning is called the sleep cognition hypothesis. In
this article the findings of research in older people are reviewed. 23 research
reports were found in which sleep was measured with polysomnography.
The findings in relatively healthy older people do not suggest a strong
association between sleep and cognition nor a causal effect between a specific
cognitive dysfunction and a specific sleep variable. The findings in demented
older people concerning sleep and cognition are inconsistent. In relatively
healthy older people a significant correlation between nocturnal respiratory
disturbance and cognitive functioning was seldom found, whereas in demented
older people a clear association was shown. Therefore, in demented older people
prudence is necessary in prescribing psychopharmaca
because these can enhance the appearance of sleep apneas.
Bedard MA, Montplaisir J, Richer F, Rouleau I, Malo J.
Obstructive sleep apnea syndrome: pathogenesis of
neuropsychological deficits.
J Clin Exp Neuropsychol. 1991 Nov;13(6):950-64.
Neuropsychological deficits
have been documented in patients with obstructive sleep apnea syndrome (OSAS).
Both nocturnal hypoxemia and impairement of daytime
vigilance have been suggested as the pathogenesis of these deficits, yet it
remains difficult to find good correlations between cognitive deficits and
either of these physiological parameters. In the present study, 10 normal
controls were compared to 10 moderately and 10 severely apneic
patients, all recorded in a sleep laboratory for two consecutive nights, with a
vigilance and neuropsychological assessment made during the intervening day. Relative
to the controls, moderate and severe OSAS showed differences in many cognitive
functions, although the severely affected showed the greater differences.
Moreover, severe apneics were also worse than
moderate apneics on tests that were found to be
normal in the latter group. This suggests a discontinuity in the appearance of
neuropsychological deficits as OSAS progresses. Further analyses revealed that reductions
in general intellectual measures, as well as in executive and psychomotor tasks
were all attributable to the severity of hypoxemia, while other attention and
memory deficits were related to vigiLance impairment.
Therefore, both vigilance impairment and nocturnal hypoxemia may differentially
contribute to the cognitive dysfunctions found in OSAS.
Bedard M-A, Montplaisir
J, Malo J, Richler F, Rouleau I. Persistent neuropsychological deficits and
vigilance impairment in sleep apnea syndrome after treatment with continuous
positive airways pressure (CPAP). J Clin Exp Neuropsychol 1993;15:330-41.
Beebe DW, Gozal D. dean.beebe@chmcc.org
Obstructive sleep apnea and the prefrontal cortex:
towards a comprehensive model linking nocturnal upper airway obstruction to
daytime cognitive and behavioral deficits.
J Sleep Res. 2002 Mar;11(1):1-16.
Obstructive
sleep apnea (OSA) is accompanied by significant daytime cognitive and
behavioral deficits that extend beyond the effects of sleepiness. This article
outlines a causal model by which to understand these psychological effects
among OSA patients. The model proposes that sleep disruption and blood gas
abnormalities prevent sleep-related restorative processes, and further induce
chemical and structural central nervous system cellular injury. This, in turn,
leads to dysfunction of prefrontal regions of the brain cortex (PFC),
manifested behaviorally in what neuropsychologists
have termed 'executive dysfunction'. Executive dysfunction is proposed to
markedly affect the functional application of cognitive abilities, resulting in
maladaptive daytime behaviors. The proposed model (1) accounts for the
specific psychological phenotype associated with OSA, (2) accommodates
developmental components in this phenotype, (3) bridges between physical and
psychological phenomena, (4) suggests mechanisms by which the nocturnal
disorder might have effects on daytime functioning, (5) is empirically
testable, (6) generates unique research hypotheses, and (7) has practical implications.
The model is intended to act as a catalyst for future research and as a
preliminary guide for clinicians.
Beebe DW, Groesz L, Wells C,
Nichols A, McGee K. dean.beebe@cchmc.org
The neuropsychological effects of obstructive sleep
apnea: a meta-analysis of norm-referenced and case-controlled data.
Sleep. 2003 May 1;26(3):298-307.
STUDY
OBJECTIVES: The research literature on the neuropsychological effects of
obstructive sleep apnea (OSA) has yielded seemingly contradictory findings, and
narrative reviews of this literature are prone to interpretive errors. We used
sophisticated meta-analytic models to minimize such errors, with the goal of
clarifying the effect of OSA on neuropsychological functioning. DESIGN:
Meta-analytic review of research through 2001. PARTICIPANTS: We reviewed
studies of neuropsychological functioning among adults with untreated OSA.
Twenty-five studies met review criteria, representing 1092 patients with OSA
and 899 healthy controls. MEASUREMENTS AND RESULTS: Two sets of effect sizes
were generated. One compared OSA group means against those of healthy controls
in case-controlled studies. The other compared all OSA group means against
published normative data. Within each data set, 10 neuropsychological outcome
domains were coded. In both data sets, untreated OSA was found to have a
negligible impact on intellectual and verbal functioning but a substantial
impact upon vigilance and executive functioning. Data were mixed with regard to
visual and motor functioning; posthoc inspection of
the data suggested that tests of fine-motor coordination or drawing were more
sensitive to OSA than were tests of fine-motor speed or visual perception. Data
were also mixed with regard to memory functioning, probably related to methodologic differences across studies. CONCLUSIONS: Etiologic
models should emphasize mechanisms known to affect vigilance, executive
functioning, and motor coordination but not intelligence, verbal functioning,
or visual perception. Clinicians should be alert to OSA symptoms in patients
with declines in vigilance, executive functioning, or coordination.
Berry DTR, Webb WB, Block AJ, Bauer RM, Switzer DA.
Nocturnal hypoxia and neuropsychological variables. J Clin
Exp Neuropsychol 1986;8:229-38.
Boland LL, Shahar E, Iber C, Knopman DS, Kuo TF, Nieto FJ;
Measures of cognitive function in persons with varying
degrees of sleep-disordered breathing: the Sleep Heart Health Study.
J Sleep Res. 2002 Sep;11(3):265-72.
Epidemiologic
literature suggests that persons with clinically diagnosed sleep apnoea frequently have impaired cognitive function, but
whether milder degrees of sleep-disordered breathing (SDB) are associated with
cognitive dysfunction in the general population is largely unknown.
Approximately 1700 subjects free of clinically diagnosed SDB underwent at-home polysomnography (PSG) as part of the Sleep Heart Health
Study (SHHS) and completed three cognitive function tests within 1-2 years of
their PSG: the Delayed Word Recall Test (DWR), the WAIS-R Digit Symbol Subtest
(DSS), and the Word Fluency test (WF). A respiratory disturbance index (RDI)
was calculated as the number of apnoeas and hypopnoeas per hour of sleep. After adjustment for age,
education, occupation, field centre, diabetes, hypertension, body-mass index,
use of CNS medications, and alcohol drinking status, there was no consistent
association between the RDI and any of the three cognitive function measures.
There was no evidence of a dose-response relation between the RDI and cognitive
function scores and the adjusted mean scores by quartiles of RDI never differed
from one another by more than 5% for any of the tests. In this sample of
free-living individuals with mostly mild to moderate levels of SDB, the degree
of SDB appeared to be unrelated to three measures of cognitive performance.
Broughton RJ, Fleming JAE, George CFP, Hill JD, Kryger MH, et al. Randomized, double-blind,
placebo-controlled crossover trial of modafinil in
the treatment of excessive daytime sleepiness in narcolepsy. Neurology
1997;49:444-51.
Cassel W, Ploch
T, Becker C, Dugnus D, Peter JH, von Wichert P. Risk of traffic accidents in patients with
sleep-disordered breathing: reduction with nasal CPAP. Eur
Respir J 1996;9:2606-2611.
Cohen-Zion M, Stepnowsky C, Marler, Shochat T, Kripke DF, Ancoli-Israel S.
Changes in cognitive function associated with sleep
disordered breathing in older people.
J Am Geriatr Soc. 2001
Dec;49(12):1622-7.
OBJECTIVES:
Sleep disordered breathing (SDB) is very common in older people and is known to
be associated with complaints of impaired daily functioning, including
excessive daytime sleepiness and cognitive impairments. As part of a larger
study on SDB and aging, it became possible to examine the relationship between
SDB and cognition in older men and women. DESIGN: A population-based
longitudinal study. SETTING: In-home interviews and home sleep recordings in
the greater
Engleman, H.M.,
Engleman HM, Kingshott
RN, Martin SE,
Cognitive function in the sleep apnea/hypopnea syndrome (SAHS).
Sleep. 2000 Jun 15;23 Suppl 4:S102-8.
The
magnitude, determinants and reversibility of cognitive deficits associated with
the sleep apnea/hypopnea syndrome (SAHS) are of
clinical and research interest. A quantitative overview of impairment effect
sizes (ESs) from case-control studies of cognitive
performance in SAHS suggests that deficits broadly worsen with disease
severity, with large average values for attentional
(ES approximately 1.0 SD units) and executive (ES approximately 0.9 SD units)
cognitive scores, and moderate values for memory-related (ES approximately 0.6
SD units) performance scores. A study of determinants of cognitive outcomes
conducted in 150 patients with SAHS (AHI 5+ and > or =2 symptoms) showed
significant but weak associations between a cognitive 'intellectual ability'
component score (CS) and both AHI (r=-0.14) and minimum oxygen saturation (r =
0.15), linking increasing disease severity with poorer performance. A somewhat
stronger correlation between a cognitive 'response slowing' CS and a
'wakefulness' CS was observed (r=-0.34). That sleepiness as well as hypoxemia
might contribute to cognitive deficit has also been suggested by experimental
sleep fragmentation in normals, producing small to
moderate impairments (average ES approximately 0.3 SD units) in attention-biased
scores. The reversibility of attentional cognitive
deficits has been investigated through a meta-analysis of randomized
placebo-controlled crossover studies of CPAP treatment, involving 98 SAHS
patients (AHI 5+ and > or =2 symptoms). While cognitive outcomes
showed at least trends towards better performance on CPAP than on placebo
(p< or =0.1), the ESs of cognitive enhancements
following CPAP were small (average ES approximately 0.2 SD units). This may
be due either to the relatively mild study population, suboptimal CPAP use or
to an irreversible component in cognitive impairment in SAHS.
Engleman
HM, Martin SE, Deary IJ, Douglas NJ.
Effect of continuous positive airway pressure treatment
on daytime function in sleep apnoea/hypopnoea
syndrome.
Lancet. 1994 Mar 5;343(8897):572-5.
Continuous
positive airway pressure (CPAP) is the treatment of choice for the sleep apnoea/hypopnoea syndrome (SAHS); it is usually given with
the aim of improving daytime cognitive function, mood, and sleepiness. However,
its efficacy has not been validated by controlled trials. We have carried out a
randomised, placebo-controlled, crossover study of
objective daytime sleepiness, symptoms, cognitive function, and mood in a
consecutive series of 32 SAHS patients with a median apnoea
plus hypopnoea frequency of 28 (range 7-129) per hour
slept. Patients were treated with 4 weeks each of CPAP and an oral placebo,
which they were
Ferini-Strambi L, Baietto C, Di Gioia
MR, Castaldi P, Castronovo
C, Zucconi M, Cappa SF. ferinistrambi.luigi@hsr.it
Cognitive dysfunction in patients with obstructive
sleep apnea (OSA): partial reversibility after continuous positive airway
pressure (CPAP).
Brain Res Bull. 2003 Jun
30;61(1):87-92.
The aims
of this study were to assess cognitive function in obstructive sleep apnea
(OSA) patients and to evaluate the effect of short- and long-term treatment
with continuous positive airway pressure treatment (CPAP). A battery of
neuropsychological tests, the Epworth Sleepiness Scale (ESS), and the Beck
Inventory Scale were administered to 23 patients with severe OSA (age:
56.5+/-6.13; AHI: 54.9+/-13.37) and to 23 age- and education-matched controls.
The OSA patients were evaluated in a baseline condition and in two follow-up
treatment sessions (after 15 days and 4 months of CPAP, respectively). At
baseline, OSA patients had a significant impairment, compared to controls, in
tests of sustained attention, visuospatial learning,
executive function, motor performance, and constructional abilities. The
longitudinal evaluation showed that after a 15-days CPAP treatment attentive, visuospatial learning, and motor performances returned to
normal levels. A 4-months CPAP treatment did not result in any further
improvement in cognitive tests. Performance on tests evaluating executive
functions and constructional abilities was not affected by short- and long-term
treatment with CPAP. The findings of this study confirm the hypothesis of
partial reversibility of cognitive dysfunction in OSA patients after CPAP.
Findley LJ, Barth JT, Powers DC, Wilhoit
SC, Boyd MS, Suratt PM. Cognitive impairment in
patients with obstructive sleep apnea and associated hypoxemia. Chest
1986;90:686-90.
Findley LJ, Fabrizio MJ, Knight
H, Norcross BB, Laforte AJ, Suratt
PM. Driving simulator performance in patients with obstructive sleep apnea. Am
Rev Respir Dis
1989;140(2):529-530.
Findley L, Unverzagt ME, Guchu R, Fabrizio M, Buckner J, Suratt P. Vigilance and automobile accidents in patients
with sleep apnea or narcolepsy. Chest 1995;108(3):619-624.
Foley DJ, Masaki K, White L, Larkin EK, Monjan A, Redline S. foleyd@gw.nia.nih.gov
Sleep-disordered breathing and cognitive impairment in
elderly Japanese-American men.
Sleep. 2003 Aug 1;26(5):596-9.
STUDY
OBJECTIVE: To assess the association between sleep-disordered breathing and
cognitive functioning in an elderly cohort of Japanese-American men. DESIGN:
Cross-sectional study. SETTING: The Honolulu-Asia Aging Study of Sleep Apnea,
Oahu, Hawaii. PARTICIPANTS: 718 men between 79 and 97 years of age examined in
1999 and 2000. MEASUREMENTS: Apnea-hypopnea index
from in-home overnight polysomnography, performance
on the Cognitive Abilities Screening Instrument, body mass index, neck
circumference, Epworth Sleepiness Scale, snoring, Center for Epidemiologic
Studies Depression 11-item depression scale, physical disability, and history of
heart disease, stroke, hypertension, diabetes, and dementia. RESULTS: Less than
30% of the men had no sleep-disordered breathing (apnea-hypopnea
index < 5) and nearly one-fifth (19%) had severe sleep-disordered breathing
(apnea-hypopnea index > or = 30). Severe
sleep-disordered breathing was associated with higher body mass index, habitual
snoring, and daytime drowsiness. No association was found between
sleep-disordered breathing and cognitive functioning, including measures of
memory function, concentration, and attention. CONCLUSIONS: Sleep-disordered
breathing was associated with more drowsiness but not with poor performance on
standardized cognitive tests used to screen for Alzheimer disease and other
dementias in older persons. Because a healthy-participant effect may have
contributed to this finding, more extensive cognitive testing may be necessary
to reveal more subtle deficits from sleep-disordered breathing.
Friedman BC, Hendeles-Amitai A, Kozminsky E, Leiberman A, Friger M, Tarasiuk A, Tal A.
Adenotonsillectomy
improves neurocognitive function in children with obstructive sleep apnea
syndrome.
Sleep. 2003 Dec 15;26(8):999-1005.
OBJECTIVE:
To evaluate neurocognitive functions of children with obstructive sleep apnea
syndrome (OSAS), before and after adenotonsillectomy,
compared with healthy controls. DESIGN: Prospective study. PATIENTS AND
METHODS: Thirty-nine children with OSAS aged 5 to 9 years (mean age, 6.8 +/-
0.2 years) and 20 healthy children (mean age, 7.4 +/- 1.4 years) who served as
controls, underwent a battery of neurocognitive tests containing
process-oriented intelligence scales. Twenty-seven children in the OSAS group
underwent follow-up neurocognitive testing 6 to 10 months after adenotonsillectomy. Fourteen children in the control group
were also reevaluated 6 to 10 months after the first evaluation. RESULTS:
Children with OSAS had lower scores compared with healthy children in some
Kaufman Assessment Battery for Children (K-ABC) subtests and in the general
scale Mental Processing Composite, indicating impaired neurocognitive function.
No correlation was found between neurocognitive performance and OSAS severity.
Six to 10 months after adenotonsillectomy, the
children with OSAS demonstrated significant improvement in sleep characteristics,
as well as in daytime behavior. Their neurocognitive performance improved
considerably, reaching the level of the control group in the subtests Gestalt
Closure, Triangles, Word Order, and the Matrix analogies, as well as in the
K-ABC general scales, Sequential and Simultaneous Processing scales, and the
Mental Processing Composite scale. The magnitude of the change expressed as
effect sizes showed medium and large improvements in all 3 general scales of
the K-ABC tests. CONCLUSIONS: Neurocognitive function is impaired in
otherwise healthy children with OSAS. Most functions improve to the level of
the control group, indicating that the impaired neurocognitive functions are
mostly reversible, at least 3 to 10 months following adenotonsillectomy.
Gale SD, Hopkins RO.
s2gale@chw.edu
Effects of hypoxia on the brain: neuroimaging
and neuropsychological findings following carbon monoxide poisoning and
obstructive sleep apnea.
J Int Neuropsychol
Soc. 2004 Jan;10(1):60-71.
Hypoxia
damages multiple organ systems especially those with high oxygen utilization
such as the central nervous system. The purpose of this study was to compare
the neuropathological and neuropsychological effects
of hypoxia in patients with either carbon monoxide poisoning or obstructive
sleep apnea. Neuroimaging revealed evidence of hippocampal atrophy in both groups although a linear
relationship between hippocampal volume and memory
performance was found only for selected tests and only in the sleep apnea
group. There were significant correlations between hippocampal
volume and performance on measures related to nonverbal/information processing.
Generalized brain atrophy, as measured by the ventricle-to-brain ratio, was
more common in the carbon monoxide poisoning group compared to the obstructive
sleep apnea group. Performance on tests of executive function improved
following treatment with nasal continuous positive airway pressure treatment in
the obstructive sleep apnea group but there was no associated improvement in
general intellectual function. We found that hypoxia due to obstructive sleep
apnea and CO poisoning resulted in neuropathological
changes and neuropsychological impairments. The observed group differences
provide insight into the relationship between etiology of injury, neuropathological changes, and clinical presentation
Gall R, Isaac L, Kryger M. Qaulity-of-life in mild obstructive sleep apnea. Sleep
1993;16:S59-61.
Gehrman PR, Martin JL, Shochat T, Nolan S, Corey-Bloom J, Ancoli-Israel
S.
Sleep-disordered breathing and agitation in
institutionalized adults with Alzheimer disease.
Am J Geriatr Psychiatry. 2003
Jul-Aug;11(4):426-33.
OBJECTIVE:
The authors examined the relationship between sleep-disordered breathing (SDB)
and agitation in patients with Alzheimer disease (AD). METHODS: Thirty-eight AD
patients (29 women, 9 men) in nursing homes in San Diego, CA participated. The
mean age was 82.3 years, with a range of 61 to 95 years. Mean Mini-Mental State
Exam score was 6.5 (range: 0-16). Sleep was recorded for one night, and
agitation was measured with behavioral observations and ratings by nursing
staff. RESULTS: SDB was very prevalent in this sample and was related to some
types of agitation during the day but not in the evening or night. Aggressive
Agitation on the Cohen-Mansfield Agitation Inventory and Manual Manipulation on
the Agitated Behavior Rating Scale were greater with more severe SDB. Searching
and wandering agitation decreased with more severe SDB. CONCLUSION: This
study supports the hypothesis that SDB is related to agitation in AD, although
the results are specific to certain types of agitation. Treatment of SDB may
decrease agitation, easing the burden of caregiving
and prolonging the time that patients are able to remain at home.
George CFP, Boudreau AC, Smiley A. Simulated driving
performance in patients with obstructive sleep apnea. Am J Respir
Crit Care Med 1996;154:175-81.
George C, Nickerson P, Hanly P,
Millar T, Kryger M. Sleep apnea patients have more
automobile accidents (Letter). Lancet 1987;i:447.
Greenberg GD, Watson RK, Deptula
D. Neuropsychological dysfunction in sleep apnea. Sleep 1987;10:254-62.
Guilleminault C, Winkle R, Korobkin R, et al. Children and nocturnal snoring:
evaluation of the effects of sleep related respiratory resistive load and
daytime functioning. Eur J Pediatr
1982;139:165.
Hararldsson PO, Carefelt C, Persson HE, Sachs C, Tornros J. Simulated long-term driving performance before
and after uvulopalatopharyngoplasty. ORL
1991;53:106-110.
Haraldsson PO, Carenfelt C, Tingvall C. Sleep
apnea syndrome symptoms and automobile driving in a general population. J Clin Epidemiol 1992;45:821-825.
Hart RP, Morin CM, Best AM. Neuropsychological performance
in elderly insomnia patients. Aging and Cognition 1995;2:268-78.
Hayward L, Mant A, Eyland A, Hewitt H, Purcell C, Turner J, et al. Sleep
Disordered Breathing and Cognitive Function in a Retirement Village Population.
Age and Ageing 1992;21:121-128.
Henry GK, Hart RP, Kwentus JA, Sicola MJ. Effects of protriptyline
on vigilance and information processing in narcolepsy. Psychopharmacol
1988;95:109-12.
Henry GK, Satz P, Heilbronner RL. Evidence of a Perceptual-Encoding Deficit
in Narcolepsy? Sleep 1993;16(2):123-27.
Kaneko Y, Hajek VE, Zivanovic V, Raboud J, Bradley
TD.
Relationship of sleep apnea to functional capacity and
length of hospitalization following stroke.
Sleep. 2003 May 1;26(3):293-7.
STUDY
OBJECTIVES: Recent evidence indicates that sleep apnea is common in patients
with stroke. We hypothesized that the presence of sleep apnea among stroke
patients would be associated with a greater degree of functional disability and
longer hospitalization following stroke. DESIGN: Prospective study. SETTING AND
PATIENTS: Sixty-one stroke patients admitted to a stroke rehabilitation unit.
INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Sleep studies were performed on
all patients, and sleep apnea was defined as an apnea-hypopnea
index of 10 or more per hour of sleep. Patients underwent functional assessments,
including the Functional Independence Measure. Sleep apnea was found in 72% of
patients; 60% had predominantly obstructive sleep apnea, while 12% had
predominantly central sleep apnea. Although the severity of stroke was similar
in the 2 groups, compared to patients without sleep apnea, those with sleep
apnea had lower functional capacity [Functional Independence Measure score
(mean +/- SEM) 80.2 +/- 3.6 versus 94.7 +/- 4.3, p < 0.05 at admission, and
101.5 +/- 2.8 versus 112.9 +/- 2.7, p < 0.05 at discharge] and spent
significantly more days in rehabilitation (45.5 +/- 2.3 versus 32.1 +/- 2.7
days, p < 0.005). In addition, multiple regression analysis showed that
obstructive sleep apnea was significantly and independently related to
functional impairment and length of hospitalization. CONCLUSIONS: Sleep
apnea is very common among stroke patients undergoing rehabilitation, and its
presence is associated with worse functional impairment and a longer period of
hospitalization and rehabilitation. These data suggest that sleep apnea may be
contributing to functional impairment and prolonged hospitalization following
stroke.
Kribbs NB, Pack AI, Kline LR, Getsy JE, Schuett JS, Henry JN,
et al. Effects of one night without nasal CPAP treatment on sleep and
sleepiness in patients with obstructive sleep apnea. Am Rev Respir
Dis 1993;147:1162-8.
Levander S, Sachs C. Vigilance
performance and autonomic function in narcolepsy: effects of central
stimulants. Psychophysiol 1985;22:24-31.
Lind MG, Lundell BP. Tonsillar hyperplasia in children. A cause of obstructive
sleep apneas, CO2 retention, and retarded growth. Arch O
Montplaisir J, Bedard MA, Richer F, Rouleau I.
Neurobehavioral manifestations in obstructive sleep apnea syndrome before and
after treatment with continuous positive airway pressure. Sleep 1992;15((Suppl)):S17-S19.
Naegele
B, Thouvard V, Pepin J-L, Levy P, Bonnet C, Perret JE, et al. Deficits of Cognitive Executive Functions
in Patients with Sleep Apnea Syndrome. Sleep 1995;18(1):43-52.
Newsom-Davis IC, Lyall RA, Leigh
PN, Moxham J, Goldstein LH.
The effect of non-invasive positive pressure
ventilation (NIPPV) on cognitive function in amyotrophic lateral sclerosis
(ALS): a prospective study.
J Neurol Neurosurg
Psychiatry. 2001 Oct;71(4):482-7.
OBJECTIVES:
Neuropsychological investigations have shown a degree of cognitive dysfunction
in a proportion of non-demented patients with ALS. Respiratory muscle weakness
in ALS can lead to nocturnal hypoventilation, resulting in sleep disturbance
and daytime somnolence. Sleep deprivation of this type may cause impairments in
cognitive function, but this has not been formally evaluated in ALS. METHODS:
Cognitive functioning was evaluated in nine patients with ALS with sleep
disturbance caused by nocturnal hypoventilation (NIPPV group), and in a
comparison group of 10 similar patients without ventilation problems (control
group). The NIPPV group then started non-invasive positive pressure ventilation
(NIPPV) at night. After about 6 weeks, change in cognitive function was
evaluated. RESULTS: Statistically significant improvement in scores on two of
the seven cognitive tests was demonstrated in the NIPPV group postventilation, and a trend towards significant improvement
was found for two further tests. Scores in the control group did not improve
significantly for these four tests, although an improvement was found on one
other test. CONCLUSIONS: Nocturnal hypoventilation and sleep disturbance may
cause cognitive dysfunction in ALS. These deficits may be partially improved by
NIPPV over a 6 week period. This has important implications for
investigations of both cognitive dysfunction in non-demented patients with ALS,
and the effect of ventilation on quality of life.
Redline S, Strauss
ME, Adams N, Winters M, Roebuck T, Spry K, et al. Neuropsychological Function
in Mild Sleep-Disordered Breathing. Sleep 1997;20(2):160-167.
Rouleau I, Decary
A, Chicoine AJ, Montplaisir
J. rouleau.isabelle@uqam.ca
Procedural skill learning in obstructive sleep apnea
syndrome.
Sleep. 2002 Jun 15;25(4):401-11.
STUDY
OBJECTIVES: To better characterize the cognitive deficits observed in
obstructive sleep apnea syndrome (OSAS) by examining procedural skill learning
abilities. DESIGN: Procedural skill learning was assessed using Mirror Tracing
and Rotary Pursuit skill learning tasks. Subjects also completed a
comprehensive neuropsychological test battery. SETTING: Cognitive testing was
performed during the day following the second of two consecutive nights during
which sleep and respiratory variables were recorded. PARTICIPANTS: Two groups
(28 OSAS patients and 18 normal controls) with equivalent mean age and
education levels. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: No significant differences
in learning rates were observed between the groups on the Rotary Pursuit Task.
On the Mirror Tracing Task, overall learning of the skill and transfer to a new
figure or to the reverse tracing direction was similar in the OSAS and NC
groups. However, there was a subgroup of OSAS subjects (n=11) who showed marked
difficulties in the initial acquisition of the Mirror Tracing Task. This
subgroup's performance was no longer significantly different from that of
controls and OSAS subjects without initial adaptation difficulty in the
subsequent trials. Performance of subjects who had difficulty with initial
adaptation on the Mirror Tracing was also significantly lower on tests of
frontal executive function, but not on episodic memory tests. Sleep and respiratory
variables did not distinguish between the two subgroups of OSAS patients.
However, none of the young OSAS subjects (<40 years) presented this deficit.
CONCLUSION: Results indicate that contrary to this study's hypothesis, OSAS
patients did not show procedural skill learning deficits. A subgroup of OSAS
patients, however, did show deficits in initial skill adaptation and
difficulties on other neuropsychological tests. Frontal dysfunction and
decrement in psychomotor efficiency and vigilance appeared to be the most
consistent explanation for characterizing the profile of neuropsychological
test results among the OSAS patients.
Salorio CF, White DA, Piccirillo J, Duntley SP, Uhles ML.
Learning, memory, and executive control in individuals
with obstructive sleep apnea syndrome.
J Clin Exp Neuropsychol. 2002 Feb;24(1):93-100.
A range of neuropsychological
deficits have been identified in individuals with obstructive sleep apnea
syndrome (OSAS) and have been related to disruptions in function of the frontal
cortex of the brain. We hypothesized that impairments in the use of strategic,
frontally-mediated processes that facilitate learning and memory would be
associated with deficits in the long-term episodic memory of verbal material
(i.e., word lists). We evaluated 28 adults with OSAS and 24 controls (ranging
from 28 to 60 years of age) using the California Verbal Learning Test. General
executive abilities were assessed using the Wisconsin Card Sorting Test, Letter
fluency, and Category fluency. Individuals with OSAS exhibited poorer recall
across learning trials, less efficient use of semantic clustering, and poorer
use of semantic cues. Retention of previously encoded information and
recognition, however, were intact. With the exception of letter fluency, deficits
were not observed in general executive control. Results are discussed within
the context of disruptions in the interactions between long-term memory and
executive abilities that are subserved by frontal and
distal brain regions.
Sateia MJ. michael.j.sateia@dartmouth.edu
Neuropsychological impairment and quality of life in
obstructive sleep apnea.
Clin Chest Med. 2003
Jun;24(2):249-59.
Although
clinical experience has suggested for more than two decades that OSA is
associated with impairment of cognition, emotional state, and quality of life
and that treatment with nasal CPAP produces significant improvements in these
areas, sound empirical evidence to support this view, especially regarding
treatment outcome, has been lacking. More recent investigations have begun to
provide this support from randomized, adequately controlled studies. These
assessments suggest that some degree of cognitive dysfunction is associated
with OSA. The effects are most apparent in the severe cases, whereas results in
mild cases are more equivocal. Reported impairments include global intellectual
dysfunction and deficits in vigilance, alertness, concentration, short- and
long-term memory, and executive and motor function. Considerable discrepancy
exists across studies with respect to type and degree of dysfunction, however.
Disturbances in general intellectual function and executive function show
strongest correlations with measures of hypoxemia. Not unexpectedly,
alterations in vigilance, alertness, and, to some extent, memory seem to
correlate more with measures of sleep disruption. Although many inadequately
controlled investigations have demonstrated reversibility of most or all of
these deficits with effective treatment, more recent placebo-controlled studies
have raised doubts regarding whether the observed changes are truly a function
of treatment. This issue requires further systematic exploration with adequate
controls and step-wise analysis of treatment duration effects. A similar set of
considerations exists with respect to the relationship between psychological
disturbance, primarily depression, and OSA. Although several studies suggest
significant depression in these patients, the results are mixed.
Placebo-controlled treatment trials fail to demonstrate consistently a
difference in mood improvement between active treatment groups and controls,
although several methodologic considerations suggest
that these results should be interpreted with caution. Numerous investigations
leave little doubt about the issue of quality of life impairment among persons
with OSA. Further characterization of impairment, particularly in areas
specific to this population, will provide clearer understanding of the problem.
Preliminary investigations of treatment response in controlled studies indicate
significantly greater improvement of quality of life in response to CPAP. Although
patients with OSA commonly report disturbances in cognitive and psychological
function and general quality of life, the increased rates of obesity,
hypertension, diabetes, cardiovascular disease, medication use, and related
psychosocial complications present a host of potential etiologies that might
explain the impairments noted. There can be little doubt that these covariants do, in some cases, contribute to
neuropsychological dysfunctions. It is essential that future studies
continue to define those disturbances that are specific to OSA, the
relationship between levels of severity and impairment, the role of treatment
in reversing these dysfunctions, and the correlation between test results and
significant day-to-day social and occupational functional impairment.
Telakivi T, Kajaste
S, Partinen M, Koskenvuo M,
Slami T, Kaprio J.
Cognitive function in middle-aged snorers and controls: role of excessive
daytime somnolence and sleep related hypoxic events. Sleep 1988;11:454-62.
Valley V, Broughton R. Daytime performance deficits and
physiological vigilance in untreated patients with narcolepsy-cataplexy
compared to controls. Rev EEG Neurophysiol
1981;1:133-9.
Xu Y, Li S, Huang X, Cong B.
[Insulin-like growth factor-I and cognitive function in
patients with obstructive sleep apnea syndrome] [Article in Chinese]
Zhonghua Yi Xue
Za Zhi. 2002 Oct
25;82(20):1388-90.
OBJECTIVE:
To explore the possible biochemical mechanism of cognitive impairment in
patients with obstructive sleep apnea syndrome (OSAS). METHODS: Polysomnography was administered to thirty-six patients
with OSAS and eighteen education and BMI-matched controls, all males aged 40
approximately 49 for 8.5 hours at night. Early next morning blood was drawn and
serum insulin-like growth factor-I (IGF-I) was determined by immunoradiometric assay. Then neuropsychological tests of
visual regeneration, digital symbol, comprehensive memory and digital span were
conducted. RESULTS: The quality of sleep in the patients with OSAS was
significantly worse than that of the controls. The score of visual regeneration
in the patients with OSAS was 8.4 +/- 2.7, significantly lower than that in
control group (11.6 +/- 1.4, P < 0.01). The score of digital symbol in
patients with OSAS was 36.92 +/- 8.31, significantly lower than that in the
controls (47.8 +/- 6.8, P < 0.01). The serum IGF-I level of the patients
with OSAS was: 127.2 +/- 87.0 ng/ml, significantly
lower than that of the controls (194.03 ng/ml +/-
77.31 ng/ml, P < 0.05). The IGF-I level was
significantly positively correlated with the scores of visual regeneration test
(r = 0.381, P < 0.05) and digital symbol test (r = 0.330, P < 0.05),
lowest SaO(2) (r = 0.371, P < 0.05), mean SaO(2) (r = 0.333, P < 0.05) and REM sleep duration (r =
0.598, P < 0.01). CONCLUSION: Decrease of serum IGF-I level may play a
role in the cognitive impairment in patients with OSAS. Nocturnal hypoxemia and
REM sleep deprivation may be the reason of the decrease of the serum IGF-I
level in patients with OSAS.
5) www.websciences.org/sleepandhealth/kryger.html:
This describes cognitive function in sleep disorders (by Meir
H. Kryger) and notes that many studies from several
countries have documented abnormalities in sleep apnea pts, including memory,
learning, intellect, and a decreased ability to initiate new mental processes
(i.e., planning).
======================================================
SLEEP APNEA and
DEPRESSION
Means MK, Lichstein KL, Edinger JD, Taylor DJ, Durrence
HH, Husain AM, Aguillard
RN, Radtke RA. mkmeans@duke.edu
Changes in depressive symptoms after continuous
positive airway pressure treatment for obstructive sleep apnea.
Sleep Breath. 2003 Mar;7(1):31-42.
It is
generally believed that obstructive sleep apnea (OSA) causes depression in some
patients, yet it is unknown whether this depression is an actual clinical
phenomenon or purely a result of overlapping somatic/physical symptoms shared
by both disorders. The present study investigated changes in both somatic and
affective/cognitive symptoms of depression associated with the introduction of
continuous positive airway pressure (CPAP) treatment for OSA. Participants were
39 outpatients (35 males, 4 females) with no current or past mental health
problems, diagnosed with OSA in a hospital sleep disorders clinic. The Beck
Depression Inventory (BDI) was administered prior to treatment and again 3
months after CPAP. Total BDI scores improved after CPAP, independent of
objectively monitored CPAP compliance rates. Both somatic and affective/
cognitive symptoms of depression improved in a similar manner after treatment.
Our findings suggest that depressive symptoms experienced by OSA patients are
not solely the result of physical OSA symptoms but include a mood component as
well. We introduce a hypothetical model to conceptualize the relationship
between OSA and depression.
Pochat MD, Ferber C, Lemoine P.
[Depressive symptoma
Encephale. 1993
Nov-Dec;19(6):601-7.
The sleep
apnea syndrome (SAS), which is defined by more than 5 apneas or hypopneas per hour of sleep (9), is quite a frequent
affection which concerns 1.4 to 10% of general population (1.7). The major
daytime complaints of the SAS are daytime sleepiness, memory and attention
disorders, headaches and asthenia especially in the morning, and sexual
impotence (9). The nocturnal manifestations are dominated by sonorous and
generally long standing snoring, increased by dorsal decubitus
and intake of alcohol, with repeated interruptions by respiratory arrests.
These manifestations are always noted but rarely spontaneously reported. The
sleep, non refreshing, is agitated and perturbed by numerous awakenings. The
findings of the clinical examination are poor: obesity is found in 2/3 of the
cases and arterial hypertension in 1/2 of the cases (20). Polygraphic
recording during sleep only permits an absolute diagnosis. This frequent
affection is a real problem of public health because of its numerous
complications (3, 10, 12, 13, 18, 21). Symptoms of depression are often found
when a patient with a SAS is examined and conversely, symptoms which evoke a
SAS can be found in the clinical examination of depressed patients. We decided
so to study the thymic and anxious status of 24
patients investigated for a SAS and submitted to a polygraphic
recording during sleep. Four clinical parameters were studied: DSM III-R
diagnosis criteria, Montgomery and Asberg Depression
Rating Scale (MADRS), Hamilton Anxiety Rating Scale (HARS) and thymasthenia rating scale of Lecrubier,
Payan and Puech. We also
reported Total Sleep Time (TST = 6.5 +/- 1.5), Apnea Hypopnea
Index (AHI = 26.7 +/- 21.6), number (2.1 +/- 2.8/h) and duration (174.2 +/-
150.8 s/h) of hypoxic events. Results showed that among 24 patients, 8 were
depressed according to DSM III-R diagnosis criteria and had MADRS > 25, 22
were anxious, 11 had a major anxiety (HARS > 15) and 15 presented thymasthenia (SET > 15). Significative
correlations existed between anxiety and depression (r = 0.82; p < 0.0001),
depression and thymasthenia (r = 0.77; p < 0.0001)
and thymasthenia and anxiety (r = 0.75; p <
0.0001). Among the 8 depressed patients a correlation existed between AHI and
depression (r = 0.72; p = 0.04), but no correlation was found between
depression and hypoxic events. These results were comparable to those of Guilleminault (10), Reynolds (21), Kales (12), Bliwise (3), Klonoff (13) and Millman (18) who studied relations between SAS and
depression. The evaluation of thymasthenia gave a
more precise typology of the depressive state associated to SAS: the type of
the mood disorder is more "blunted" and "anhedonic"
than "sorrowful", particularly characterised
by asthenia, lack of energy, reduction of interests (leisures,
libido, work), loss of initiative, difficulties to organise
tasks, fall of performances and reduction of pleasure usually felt in pleasant
events (15). The physic symptoma
============================================================
SLEEP DEPRIVATION AND
COGNITION
Drummond SP, Brown GG, Gillin
JC, Stricker JL, Wong EC, Buxton RB.
Altered brain response to verbal learning following
sleep deprivation.
Nature. 2000 Feb 10;403(6770):655-7.
The
effects of sleep deprivation on the neural substrates of cognition are poorly
understood. Here we used functional magnetic resonance imaging to measure the
effects of 35 hours of sleep deprivation on cerebral activation during verbal
learning in normal young volunteers. On the basis of a previous hypothesis, we
predicted that the prefrontal cortex (PFC) would be less responsive to
cognitive demands following sleep deprivation. Contrary to our expectations,
however, the PFC was more responsive after one night of sleep deprivation than
after normal sleep. Increased subjective sleepiness in sleep-deprived
subjects correlated significantly with activation of the PFC. The temporal
lobe was activated after normal sleep but not after sleep deprivation; in
contrast, the parietal lobes were not activated after normal sleep but were
activated after sleep deprivation. Although sleep deprivation significantly
impaired free recall compared with the rested state, better free recall in
sleep-deprived subjects was associated with greater parietal lobe activation.
These findings show that there are dynamic, compensatory changes in cerebral
activation during verbal learning after sleep deprivation and implicate the PFC
and parietal lobes in this compensation.
Falleti MG, Maruff
P, Collie A, Darby DG, McStephen M. mfalleti@hotmail.com
Qualitative similarities in cognitive impairment
associated with 24 h of sustained wakefulness and a blood alcohol concentration
of 0.05%.
J Sleep Res. 2003 Dec;12(4):265-74.
Previous
studies that have quantified fatigue-related cognitive impairment as blood
alcohol concentration (BAC) equivalents have been limited by two issues: the
effect of practice on tests of cognition and, more importantly, the statistic
used to quantify change in cognitive performance. The current study addressed
these issues by adopting an ABACA design, which allowed for the adequate
control of practice effects, and by using effect size metrics, which enabled
direct comparisons to be made in performance impairments as a result of fatigue
(i.e. sustained wakefulness of 24 h) and alcohol (i.e. BAC of 0.05%). Cognitive
performance under the fatigue and alcohol conditions required the use of the CogState battery. It was demonstrated that fatigue caused
greater impairment than alcohol on the speed of continuous attention and memory
and learning, and on the accuracy of complex matching. Alcohol was more
detrimental than fatigue only on the accuracy of memory and learning.
Performances on the remaining tasks were the same for both the fatigue and
alcohol conditions. These differences and similarities in performance
impairment are discussed emphasizing the deleterious cognitive effects of
relatively short periods of sustained wakefulness.
Forest G, Godbout R.
Effects of sleep deprivation on performance and EEG
spectral analysis in young adults.
Brain Cogn. 2000
Jun-Aug;43(1-3):195-200.
Nine
totally sleep deprived (TSD) and nine control subjects were evaluated with a
complete battery for attention and memory performance. Frontal and temporal
EEGs (5 min, eyes closed) were also recorded before and after the night. TSD
subjects exhibited three performance deficits: learning the Pursuit Rotor Task,
implicit recall of paired words, and distractibility on the Brown-Peterson
Test. Relative to evening recordings, control subjects showed decreased morning
absolute powers in all electrodes for all frequencies except for Frontal delta;
TSD subjects showed increased Frontal and Temporal theta and Frontal beta.
These results show that motor procedural, implicit memory, and working
memory are sensitive to one night of TSD, and that Frontal and Temporal theta
spectral power seem to discriminate between a night with sleep from a night
without.
Frey R, Decker K, Reinfried L, Klosch G, Saletu B, Anderer P, Semlitsch HV, Seidler D, Laggner AN. Richard.Frey@akh-wein.ac.at
Effect of rest on physicians' performance in an
emergency department, objectified by electroencephalographic analyses and
psychometric tests.
Crit Care Med. 2002
Oct;30(10):2322-9.
OBJECTIVE:
The aim of the field study was to objectify physicians' vigilance, well-being,
and cognitive performance in the course of 24-hr shifts with and without
afternoon rest. SUBJECTS, SETTING, AND DESIGN: Eleven residents (four women,
seven men; age, 33.5 +/- 4.7 yrs) were observed when doing two regular 24-hr
shifts at the emergency department (randomized crossover design): one without
rest, the other with a period of rest in the early afternoon (duration, 2:31
+/- 1:04 hrs) and the opportunity of having a nap (duration, 1:07 +/- 0:26 hrs,
n = 6). Electroencephalography and psychometric tests were carried out at 8 am
and at midnight. MEASUREMENTS: Measurements included subjective perception of
workload, stress, and sleeping behavior; computer-analyzed
electroencephalography; adjective checklist (Eigenschaftsworterliste
60 S, a self-rating scale); complex reaction time test; Pauli
test (number of calculations during 3 mins); and numerical
memory test. RESULTS: Electroencephalographic analyses showed a significant
decrease in alpha power and a significant increase in beta power in the evening
as compared with the morning on both days. The nocturnal increase observed in
delta activity was significantly less pronounced in duties with rest than in
duties without rest. Physicians felt deactivated at night. The Eigenschaftsworterliste 60 S indicated deactivation at
night and a rest-induced activation in the subgroup that had taken the opportunity
to sleep in the afternoon. Psychometric tests did not show any significant
differences, neither between performance in the morning and evening nor between
results with and without rest. CONCLUSION: As expected,
electroencephalographic recordings showed nocturnal deactivation and a
vigilance-promoting effect of the afternoon rest. These objective findings were
in accordance with the results derived from self-rating scales. On the other
hand, in short-lasting psychometric tests, performance was found unchanged
after 16 hrs of routine work. In further studies, a discrimination between
resting periods with and without sleep will be important.
Halbach MM, Spann CO, Egan G.
Effect of sleep deprivation on medical resident and
student cognitive function: A prospective study.
Am J Obstet Gynecol.
2003 May;188(5):1198-201.
OBJECTIVE:
The purpose of this study was to determine whether cognitive function test
results decrease after a typical night of on-call duty, on the basis of the
amount of sleep that is obtained. STUDY DESIGN: Two standard cognitive
functions tests (the Grooved Pegboard and California Verbal Learning Test II)
were administered to the 30 participants who were members of the obstetrics and
gynecology house staff and to medical students at Emory University School of
Medicine. Each test was administered twice, before and after on-call duty. The
data were analyzed with a paired two-tailed Student t test. RESULTS: For the
California Verbal Learning Test II, trial 5 showed a decrease in score of 0.8
(P =.05) after on-call duty. Trials 1 through 5 showed a decrease in score of
3.5 (P =.01). CONCLUSION: This finding suggests that cognitive function test
scores do decrease after on-call duty. Scrutiny of this issue by the
Accreditation Council of Graduate Medical Education is justified, and the issue
should continue to be evaluated. Our finding suggests that a change in our
current educational structure is warranted.
Kim DJ, Lee HP, Kim MS, Park YJ, Go HJ, Kim KS, Lee SP, Chae JH, Lee CT. kdj922@chollian.net
The effect of total sleep deprivation on cognitive
functions in normal adult male subjects.
Int J Neurosci.
2001 Jul;109(1-2):127-37.
This
study was conducted to evaluate the effect of acute sleep deprivation on
cognitive functions. A total of 18 healthy right handed males were deprived of
sleep for 24 hours. Luria-Nebraska Neuropsychological
Battery and calculation & digit-span subtest of K-WAIS were administered
before and after sleep deprivation in order to examine the changes of cognitive
functions. There were no differences in freedom from distractibility, tacile function, visual function, reading, writing,
arithmetic and intellectual process function. However, the cognitive functions
such as motor, rhythm, receptive & expressive speech, memory and complex
verbal arithmetic function were decreased after sleep deprivation. All of these
functions are known to be related to the right anterior hemisphere. For localization
scales, the scores of right frontal and right temporal dysfunction scale were
increased after sleep deprivation. These results indicate that sleep
deprivation has a negative effect on cognitive functions, especially those
associated with right anterior hemisphere or subcortical
areas.
Lee HJ, Kim L, Suh KY.
Cognitive deterioration and changes of P300 during
total sleep deprivation.
Psychiatry Clin Neurosci. 2003 Oct;57(5):490-6.
The study
was conducted to evaluate the cognitive deteriorations induced by sleep
deprivation with the computerized neurocognitive tests and the P300
event-related potential. Thirty healthy college students (22 men, eight women)
participated in the present study. Subjects remained awake for 38 h under
continuous surveillance. In the morning and the evening of the two study days,
the computerized neurocognitive tests and the P300 were performed. In vigilance
test and reaction unit test, there were significant cognitive impairments
during sleep deprivation. However, in the cognitrone
test there was significant functional improvement, which might be due to the
practice effect. The P300 latency was significantly prolonged and the
amplitudes decreased during sleep deprivation. The cognitive impairment during
38 h of sleep deprivation was mainly in terms of vigilance and reaction time.
In contrast, higher complex cognitive function such as fine perceptual
analyses, visual discrimination and working memory might be not affected by 38
h of total sleep deprivation. The changes of P300 were significantly
correlated with the results of vigilance and reaction unit tests but not with
the cognitrone test. Taken together, these results
suggest that the P300 changes that occur during sleep deprivation are a
reflection of the decrement in vigilance, which prolongs reaction time.
Lieberman HR, Tharion WJ, Shukitt-Hale B, Speckman KL, Tulley R. harris.lieberman@na.amedd.army.mil
Effects of caffeine, sleep loss, and stress on
cognitive performance and mood during U.S. Navy SEAL training. Sea-Air-Land.
Psychopharmacology (Berl). 2002
Nov;164(3):250-61. Epub 2002 Sep 05.
RATIONALE:
When humans are acutely exposed to multiple stressors, cognitive performance is
substantially degraded. Few practical strategies are available to sustain
performance under such conditions. OBJECTIVE: This study examined whether
moderate doses of caffeine would reduce adverse effects of sleep deprivation
and exposure to severe environmental and operational stress on cognitive
performance. METHODS: Volunteers were 68 U.S. Navy Sea-Air-Land (SEAL)
trainees, randomly assigned to receive either 100, 200, or 300 mg caffeine or
placebo in capsule form after 72 h of sleep deprivation and continuous exposure
to other stressors. Cognitive tests administered included scanning visual vigilance,
four-choice visual reaction time, a matching-to-sample working memory task and
a repeated acquisition test of motor learning and memory. Mood state,
marksmanship, and saliva caffeine were also assessed. Testing was conducted 1
and 8 h after treatment. RESULTS: Sleep deprivation and environmental stress
adversely affected performance and mood. Caffeine, in a dose-dependent manner,
mitigated many adverse effects of exposure to multiple stressors. Caffeine (200
and 300 mg) significantly improved visual vigilance, choice reaction time,
repeated acquisition, self-reported fatigue and sleepiness with the greatest
effects on tests of vigilance, reaction time, and alertness. Marksmanship, a
task that requires fine motor coordination and steadiness, was not affected by
caffeine. The greatest effects of caffeine were present 1 h
post-administration, but significant effects persisted for 8 h. CONCLUSIONS:
Even in the most adverse circumstances, moderate doses of caffeine can improve
cognitive function, including vigilance, learning, memory, and mood state. When
cognitive performance is critical and must be maintained during exposure to
severe stress, administration of caffeine may provide a significant advantage.
A dose of 200 mg appears to be optimal under such conditions.
Owen G, Turley H, Casey A. Gail.Owen@Unilever.com
The role of blood glucose availability and fatigue in
the development of cognitive impairment during combat training.
Aviat Space Environ Med. 2004 Mar;75(3):240-6.
INTRODUCTION: The aim of this
study was to determine whether inadequate nutrition would produce a reduction
in the blood glucose concentration and impair cognitive function. METHODS:
Energy intake, blood glucose, and cognitive function were measured in 18 male
subjects during a 4-d military field exercise. Baseline measures of fasting
blood glucose, body mass, cognitive function, and mood were taken before the
start of combat training. Measurements of blood glucose, cognition, and
well-being were then repeated during every subsequent 24 h period. Activity
levels were monitored continuously using wrist-worn activity monitors. RESULTS:
Subjects experienced an increase in symptoms relating to hypoglycemia after 24
h in the field (p < 0.01), vigor decreased (p < 0.001), and fatigue increased
(p < 0.001). After 48 h, subjects reported feelings of depression (p <
0.05), anger (p < 0.01), and confusion (p < 0.001). Delayed memory recall
was significantly impaired after 48 h (p < 0.05), and there was a decrease
in vigilance (p < 0.01). Between 48 and 72 h, there was a decrease in
immediate memory recall (p < 0.05). Delayed memory recall and vigilance
remained impaired, but did not deteriorate further. When subjects were
extracted from the field after 96 h, nude BM had decreased by 2% (p < 0.05).
CONCLUSION: Although it was possible to reproduce the symptoms and cognitive
impairment associated with hypoglycemia, there was no change in blood glucose
concentration throughout the 4-d period. The impairment in cognitive
function is likely to have been the result of significant sleep deprivation.
Pilcher JJ, Huffcutt
AI.
Effects of sleep deprivation on performance: a
meta-analysis.
Department of Psychology, Bradley University, Peoria,
Illinois 61625, USA.
Sleep. 1996 May;19(4):318-26.
To
quantitatively describe the effects of sleep loss, we used meta-analysis, a
technique relatively new to the sleep research field, to mathematically
summarize data from 19 original research studies. Results of our analysis of
143 study coefficients and a total sample size of 1.932 suggest that overall
sleep deprivation strongly impairs human functioning. Moreover, we found that
mood is more affected by sleep deprivation than either cognitive or motor
performance and that partial sleep deprivation has a more profound effect on
functioning than either long-term or short-term sleep deprivation. In general,
these results indicate that the effects of sleep deprivation may be
underestimated in some narrative reviews, particularly those concerning the
effects of partial sleep deprivation.
Sagaspe P, Charles
A, Taillard J, Bioulac B,
Philip P.
[Inhibition and working memory: effect of acute sleep
deprivation on a random letter generation task] [Article in French]
Can J Exp Psychol. 2003 Dec;57(4):265-73.
The literature contains
inconsistent data on the effects of acute sleep deprivation on the superior
cognitive functions. The primary purpose of this study is to determine the
effectiveness of inhibition, one of the functions of the working memory
executive centre (EC), over an extended, 36-hour waking period. Inhibition is a
cognitive mechanism whereby individuals ignore non-relevant information
recorded in their working memory. We also tested the effects of a 36-hour
period of acute sleep deprivation on simple reaction time. Twelve young,
healthy volunteers (M = 21.5 years, sigma = 2.3) performed a random generation
task involving letters and a simple reaction time psychomotor test over four
sessions held at 10-hour intervals. Each participant was assigned a "constant
routine." Participants were kept awake in a prone position within a room
whose environment was held strictly constant (light, noise, temperature, meals,
etc.). This control procedure provided assurance that any variation in
participant performance was solely caused by sleep deprivation. The random
generation task, nearly two minutes in length, consisted in verbally producing
a sequence of 100 letters in a random fashion (i.e. by inhibiting, for example,
alphabetical order) and by keeping to a set rhythm. Our assumption was that
capacity for inhibition diminished as the number of hours of sleep deprivation
increased. The simple reaction test, 10 minutes in length, involved pressing a
button as swiftly as possible to cause a black square to disappear from a
screen. In this case our assumption was that acute sleep deprivation alters
simple reaction time. Analysis of variance (ANOVA) through repeated measures
using the "sessions" factor as an intra-subject variable showed no
significant changes in randomization indices of the random generation task,
contrary to analysis of average simple reaction times. Participants' reaction
times deteriorated over the first two minutes of the test during the night they
were deprived of sleep. It would seem that the contradictory results of
previous studies of the effects of acute sleep deprivation on the inhibition
function would be due to errors in factor identification. In conclusion, the
inhibition function, as measured during the performance of a brief task, seems
to remain intact during an extended, 36-hour waking period. Simple reaction
time assessed by means of a brief psychomotor test is affected during a night
of sleep deprivation. The working-memory inhibition executive function shows
greater resistance to acute sleep deprivation than does psychomotor reaction
time for the performance of short tasks.
Smith ME, McEvoy LK, Gevins A.
Michael@eeg.com
The impact of moderate sleep loss on neurophysiologic
signals during working-memory task performance.
Sleep. 2002 Nov 1;25(7):784-94.
STUDY
OBJECTIVES: This study examined how sleep loss affects neurophysiologic signals
related to attention and working memory. DESIGN: Subjective sleepiness,
resting-state electroencephalogram, and behavior and electroencephalogram
during performance of working-memory tasks were recorded in a within-subject,
repeated-measures design. SETTING: Data collection occurred in a computerized
laboratory setting. Participants: Sixteen healthy adults (mean age, 26 years; 8
female) Interventions: Data from alert daytime baseline tests were compared
with data from tests during a late-night, extended-wakefulness session that
spanned up to 21 hours of sleep deprivation. MEASUREMENTS AND RESULTS:
Alertness measured both subjectively and electrophysiologically
decreased monotonically with increasing sleep deprivation. A lack of
alertness-related changes in electroencephalographic measures of the overall
mental effort exerted during task execution indicated that participants
attempted to maintain high levels of performance throughout the late-night
tests. Despite such continued effort, responses became slower, more variable,
and more error prone within 1 hour after participants' normal time of sleep
onset. This behavior failure was accompanied by significant degradation of
event-related brain potentials related to the transient focusing of attention.
CONCLUSIONS: Moderate sleep loss compromises the function of neural circuits
critical to subsecond attention allocation during
working-memory tasks, even when an effort is made to maintain wakefulness and
performance. Multivariate analyses indicate that combinations of
working-memory-related behavior and neurophysiologic measures can be sensitive
enough to permit reliable detection of such effects of sleep loss in individuals.
Similar methods might prove useful for assessment of functional alertness in
patients with sleep disorders.
Thomas M, Sing H, Belenky G,
Holcomb H, Mayberg H, Dannals
R, Wagner H, Thorne D, Popp K, Rowland L, Welsh A, Balwinski
S, Redmond D. maria.thomas@na.amedd.army.mil
Neural basis of alertness and cognitive performance
impairments during sleepiness. I. Effects of 24 h of sleep deprivation on
waking human regional brain activity.
J Sleep Res. 2000 Dec;9(4):335-52.
The
negative effects of sleep deprivation on alertness and cognitive performance
suggest decreases in brain activity and function, primarily in the thalamus, a subcortical structure involved in alertness and attention,
and in the prefrontal cortex, a region subserving
alertness, attention, and higher-order cognitive processes. To test this
hypothesis, 17 normal subjects were scanned for quantifiable brain activity
changes during 85 h of sleep deprivation using positron emission tomography
(PET) and (18)Fluorine-2-deoxyglucose ((18)FDG), a marker for regional cerebral
metabolic rate for glucose (CMRglu) and neuronal
synaptic activity. Subjects were scanned prior to and at 24-h intervals during
the sleep deprivation period, for a total of four scans per subject. During
each 30 min (18)FDG uptake, subjects performed a sleep deprivation-sensitive
Serial Addition/Subtraction task. Polysomnographic
monitoring confirmed that subjects were awake. Twenty-four hours of sleep
deprivation, reported here, resulted in a significant decrease in global CMRglu, and significant decreases in absolute regional CMRglu in several cortical and subcortical
structures. No areas of the brain evidenced a significant increase in absolute
regional CMRglu. Significant decreases in relative
regional CMRglu, reflecting regional brain reductions
greater than the global decrease, occurred predominantly in the thalamus and
prefrontal and posterior parietal cortices. Alertness and cognitive performance
declined in association with these brain deactivations. This study provides
evidence that short-term sleep deprivation produces global decreases in
brain activity, with larger reductions in activity in the distributed cortico-thalamic network mediating attention and
higher-order cognitive processes, and is complementary to studies demonstrating
deactivation of these cortical regions during NREM and REM sleep.
Wesensten NJ, Belenky G, Kautz MA, Thorne DR, Reichardt RM, Balkin TJ.
nancy.wesensten@na.amedd.army.mil
Maintaining alertness and performance during sleep
deprivation: modafinil versus caffeine.
Psychopharmacology (Berl). 2002
Jan;159(3):238-47. Epub 2001 Oct 19.
RATIONALE:
The performance and alertness effects of modafinil
were evaluated to determine whether modafinil should
replace caffeine for restoring performance and alertness during total sleep
deprivation in otherwise healthy adults. OBJECTIVES: Study objectives were to
determine (a) the relative efficacy of three doses of modafinil
versus an active control dose of caffeine 600 mg; (b) whether modafinil effects are dose-dependent; and (c) the extent to
which both agents maintain performance and alertness during the circadian
trough. METHODS: Fifty healthy young adults remained awake for 54.5 h (from
6:30 a.m. day 1 to 1:00 p.m. on day 3) and performance and alertness tests were
administered bi-hourly from 8:00 a.m. day 1 until 10:00 p.m. day 2. At 11:55
p.m. on day 2 (after 41.5 h awake), subjects received double blind
administration of one of five drug doses: placebo; modafinil
100, 200, or 400 mg; or caffeine 600 mg ( n=10 per group), followed by hourly
testing from midnight through 12:00 p.m. on day 3. RESULTS: Performance and
alertness were significantly improved by modafinil
200 and 400 mg relative to placebo, and effects were comparable to those
obtained with caffeine 600 mg. Although a trend toward better performance at
higher modafinil doses suggested a dose-dependent
effect, differences between modafinil doses were not
significant. Performance enhancing effects were especially salient during the
circadian nadir (6:00 a.m. through 10:00 a.m.). Few instances of adverse
subjective side effects (nausea, heart pounding) were reported. CONCLUSIONS: Like
caffeine, modafinil maintained performance and
alertness during the early morning hours, when the combined effects of sleep
loss and the circadian trough of performance and alertness trough were
manifest. Thus, equivalent performance- and alertness-enhancing effects were
obtained with drugs possessing different mechanisms of action. However, modafinil does not appear to offer advantages over caffeine
(which is more readily available and less expensive) for improving performance
and alertness during sleep loss in otherwise normal, healthy adults.
Moderate sleep deprivation produces impairments in
cognitive and motor performance equivalent to legally prescribed levels of
alcohol intoxication.
Williamson AM, Feyer AM. a.williamson@unsw.edu.au
Occup Environ Med. 2000
Oct;57(10):649-55.
OBJECTIVES:
To compare the relative effects on performance of sleep deprivation and
alcohol. METHODS: Performance effects were studied in the same subjects over a
period of 28 hours of sleep deprivation and after measured doses of alcohol up
to about 0.1% blood alcohol concentration (BAC). There were 39 subjects, 30
employees from the transport industry and nine from the army. RESULTS: After
17-19 hours without sleep, corresponding to 2230 and 0100, performance on some
tests was equivalent or worse than that at a BAC of 0.05%. Response speeds were
up to 50% slower for some tests and accuracy measures were significantly poorer
than at this level of alcohol. After longer periods without sleep, performance
reached levels equivalent to the maximum alcohol dose given to subjects (BAC of
0. 1%). CONCLUSIONS: These findings reinforce the evidence that the fatigue
of sleep deprivation is an important factor likely to compromise performance of
speed and accuracy of the kind needed for safety on the road and in other industrial
settings.
FATIGUE
Predicting the short-term course of fatigue symptoms:
Does adjustment of habitual coping strategies matter?
Denise de Ridder ; Paul Leseman ; Angelique de Rijk
British Journal of Health Psychology Volume: 9 Part: 1 Page: 67 -- 80
The
present study investigated whether adjustment of coping strategies would
predict the six-week course of fatigue symptoms in a primary care sample (N =
221) and whether the contribution of adjusting coping strategies would depend
on the duration of fatigue at the time. It was hypothesized that the motivation
to adjust coping strategies would be most present in people who are confronted
with the possibility of their symptoms turning into a chronic condition, and
not in people who have been fatigued for either a short period or a very long
period. Moreover, it was hypothesized that adjustments in the employment of
coping strategies are a better predictor of fatigue course than the continued
use of particular coping strategies. Using a prospective design with a six-week
follow-up, the results of a multisample LISREL
analysis over four groups of participants differing in fatigue duration showed
that adjustment of coping strategies is a significant predictor of the course
of fatigue symptoms, and that a differential effect related to fatigue duration
is present. Findings are discussed in the context of the role of coping in
regulating psychosomatic symptoms.
Aviat Space Environ Med. 2004 Mar;75(3):240-6.
The role of blood glucose availability and fatigue in
the development of cognitive impairment during combat training.
Owen G, Turley H, Casey A.
Gail.Owen@Unilever.com
INTRODUCTION:
The aim of this study was to determine whether inadequate nutrition would
produce a reduction in the blood glucose concentration and impair cognitive
function. METHODS: Energy intake, blood glucose, and cognitive function were
measured in 18 male subjects during a 4-d military field exercise. Baseline
measures of fasting blood glucose, body mass, cognitive function, and mood were
taken before the start of combat training. Measurements of blood glucose,
cognition, and well-being were then repeated during every subsequent 24 h
period. Activity levels were monitored continuously using wrist-worn activity
monitors. RESULTS: Subjects experienced an increase in symptoms relating to
hypoglycemia after 24 h in the field (p < 0.01), vigor decreased (p <
0.001), and fatigue increased (p < 0.001). After 48 h, subjects reported
feelings of depression (p < 0.05), anger (p < 0.01), and confusion (p
< 0.001). Delayed memory recall was significantly impaired after 48 h (p
< 0.05), and there was a decrease in vigilance (p < 0.01). Between 48 and
72 h, there was a decrease in immediate memory recall (p < 0.05). Delayed
memory recall and vigilance remained impaired, but did not deteriorate further.
When subjects were extracted from the field after 96 h, nude BM had decreased
by 2% (p < 0.05). CONCLUSION: Although it was possible to reproduce the
symptoms and cognitive impairment associated with hypoglycemia, there was no
change in blood glucose concentration throughout the 4-d period. The impairment
in cognitive function is likely to have been the result of significant sleep
deprivation.