Sleeping In on Weekends Might Help You Catch Up From the Week

Neurobehavioral Dynamics Following Chronic Sleep Restriction: Dose-Response Effects of One Night for Recovery. Objective: Establish the dose-response relationship between increasing sleep durations in a single night and recovery of neurobehavioral functions following chronic sleep restriction. Design: Intent-to-treat design in which subjects were randomized to 1 of 6 recovery sleep doses (0, 2, 4, 6, 8, or 10 h TIB) for 1 night following 5 nights of sleep restriction to 4 h TIB. Setting: Twelve consecutive days in a controlled laboratory environment. Participants: N = 159 healthy adults (aged 22-45 y), median = 29 y).Interventions: Following a week of home monitoring with actigraphy and 2 baseline nights of 10 h TIB, subjects were

randomized to either sleep restriction to 4 h TIB per night for 5 nights followed by randomization to 1 of 6 nocturnal acute recovery sleep conditions (N = 142), or to a control condition involving 10 h TIB on all nights (N = 17).Measurements and Results: Primary neurobehavioral outcomes included lapses on the Psychomotor Vigilance Test (PVT), subjective sleepiness from the Karolinska Sleepiness Scale (KSS), and physiological sleepiness from a modified Maintenance of Wakefulness Test (MWT). Secondary outcomes included psychomotor and cognitive speed as measured by PVT fastest RTs and number correct on the Digit Symbol Substitution Task (DSST), respectively, and subjective fatigue from the Profile of Mood States (POMS). The dynamics of neurobehavioral outcomes following acute recovery sleep were statistically modeled across the 0 h-10 h recovery sleep doses. While TST, stage 2, REM sleep and NREM slow wave energy (SWE) increased linearly across recovery sleep doses, best-fitting neurobehavioral recovery functions were exponential across recovery sleep doses for PVT and KSS outcomes, and linear for the MWT. Analyses based on return to baseline and on estimated intersection with control condition means revealed recovery was incomplete at the 10 h TIB (8.96 h TST) for PVT

performance, KSS sleepiness, and POMS fatigue. Both TST and SWE were elevated above baseline at the maximum recovery dose of 10 h TIB. Conclusions: Neurobehavioral deficits induced by 5 nights of sleep restricted to 4 h improved monotonically as acute recovery sleep dose increased, but some deficits remained after 10 h TIB for recovery. Complete recovery from such sleep restriction may require a longer sleep period during 1 night, and/or multiple nights of recovery sleep. It appears that acute recovery from chronic sleep restriction occurs as a result of elevated sleep pressure evident in both increased SWE and TST. Keywords: Recovery sleep, sleep dose response, chronic sleep restriction, neurobehavioral, homeostatic sleep drive, sleep duration, sleep deprivation, sleep loss, sleep need, PVT, KSS,  MWT 1Division of Sleep and Chronobiology, Department of Psychiatry, University of Pennsylvania School of Medicine, Philadelphia, PA; 2Centre for Sleep Research, University of South Australia, Adelaide, South Australia, Australia; 3Sleep and Performance Research Center, Washington State University, Spokane, WA; 4Biomedical Statistical Consulting, Wynnewood, PA.

news from:  ~   David F. Dinges, Ph.D., is a major American sleep researcher and teacher. He is Professor of Psychology in Psychiatry, Chief of the Division of Sleep and Chronobiology in the Department of Psychiatry, and Associate Director of the Center for Sleep and Respiratory Neurobiology in the University of Pennsylvania School of Medicine. Dr. Dinges earned his M.S. (1974) and Ph.D. (1976) degrees in Experimental Physiological Psychology from Saint Louis University. Dr. Dinges has served as President of the Sleep Research Society,  on the Boards of Directors of the American Academy of Sleep Medicine and the National Sleep Foundation, as President of the World Federation of Sleep Research and Sleep Medicine Societies and as Editor-in-Chief of SLEEP, the leading scientific journal on sleep research and sleep medicine. His laboratory studies the physiological, cognitive and functional changes resulting from sleep loss in humans. His research has primarily focused on the manner in which sleep homeostasis and circadian rhythmicity control cognitive, affective, behavioral, endocrine and

immunological processes. Dr. Dinges’ work has contributed to our knowledge of the effects of sleep disorders, the recovery potential of naps, the nature of sleep inertia and the impact of cumulative sleep debt. He has developed technologies for monitoring human neurobehavioral capability, such as his patented Psychomotor Vigilance Test (PVT). He has consulted with many U.S. agencies including the Department of Transportation, National Institutes of Health, NASA and the military as well as several non-federal, private and foreign entities on the physiological and behavioral effects of sleep deprivation, and ways to mitigate these effects. Dr. Dinges’ CV in November 2007 showed 130 peer reviewed research publications dated 1972 to 2007 as well as more than 90 editorials, reviews, chapters and committee reports, 1978 to 2007. Together with R. J. Broughton, he edited Sleep and Alertness: Chronobiological, Behavioral and Medical Aspects of Napping, Raven Press, New York, 1989. Together with M. P. Szuba and J. D. Kloss, he edited Insomnia: Principles and Management, Cambridge University Press, New York, 2003. Videos of his short Science Network lectures Behaving without sleep: Biological limits on our environmental demands and Napping and Recovery at the Salk Institute, 09 and 10 February 2007, can be viewed online. ~   GoodNews International

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