Lecture 8 - Mednick Restorative Naps NatNeuroscience 2002

Lecture 8 - Mednick Restorative Naps NatNeuroscience 2002 -...

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As life in our culture becomes more demanding, average nightly sleep is decreasing in all segments of the population (Stein, M., National Sleep Foundation Poll, 2001, www.sleepfoundation.org/ PressArchives/lessfun_lesssleep.html). ‘Power naps’—brief periods of daytime sleep lasting an hour or less—improve alertness, pro- ductivity and mood 1,2 , especially under sleep-deprived conditions 3,4 , during nightshift work 5 and during prolonged periods of driving 6 . Although naps have been shown to enhance psychomotor speed as well as short-term memory acquisition 7,8 , the effect of daytime naps on previously learned information is not known. The finding that power naps are common among people reporting daily informa- tion overload indicates that napping supports a previously unknown mechanism of off-line information processing, perhaps related to that which normally occurs during nocturnal sleep 9–16 . We investigated the phenomenon of information overload at the perceptual level. Typically in visual perception tasks, fast learn- ing happens in the first minutes to hours of training 17,18 . Previous studies using a visual texture discrimination task (TDT) 19 show that a slower phase of perceptual learning also exists, which depends on nocturnal sleep after training 9,14,19–22 . The slow phase of improvement becomes evident only after at least six hours of nocturnal sleep 14 , and sleep deprivation the night after training eliminates the normal post-sleep improvement, even when mea- sured after two full nights of recovery sleep 15 . The improvement seen in subjects who sleep for eight hours during the night after training correlates with the proportion of deep, slow wave sleep (SWS) in the first quarter of the night and with the proportion of rapid eye movement sleep (REM) in the last quarter 14 . These results indicate that a full night of sleep is important for maintenance and consolidation of experience-dependent learning, and that without at least six hours of sleep, this potential consolidation is lost. These studies do not, however, address the question of how power naps of an hour or less could aid in such information processing. Here we show that perceptual performance declined on the TDT with repeated, within-day training. In the context of this The restorative effect of naps on perceptual deterioration Sara C. Mednick 1 , Ken Nakayama 1 , Jose L. Cantero 2 , Mercedes Atienza 2 , Alicia A. Levin 2 , Neha Pathak 2 and Robert Stickgold 2 1 Department of Psychology, Harvard University, 33 Kirkland Street, Cambridge, Massachusetts 02138, USA 2 Laboratory of Neurophysiology and Department of Psychiatry, Massachusetts Mental Health Center, Harvard Medical School, 74 Fenwood Road, Boston, Massachusetts 02115, USA Correspondence should be addressed to S.C.M. ([email protected]) Published online: 28 May 2002, doi:10.1038/nn864 Human performance on visual texture discrimination tasks improves slowly (over days) in the absence of additional training. This ‘slow learning’ requires nocturnal sleep after training and is lim-
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This note was uploaded on 10/05/2009 for the course PSYCH 133 taught by Professor Mathewwalker during the Fall '09 term at Berkeley.

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Lecture 8 - Mednick Restorative Naps NatNeuroscience 2002 -...

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