Power nap
Encyclopedia
A power nap is a short sleep
which terminates before the occurrence of deep sleep or slow-wave sleep
(SWS), intended to quickly revitalize the subject. The expression was coined by Cornell University
social psychologist James Maas
.
.
Various durations are recommended for power naps, which are very short compared to regular sleep. The short duration of a power nap is designed to prevent nappers from sleeping so long that they enter a normal sleep cycle without being able to complete it. Entering a normal sleep cycle, but failing to complete it, can result in a phenomenon known as sleep inertia
, where one feels groggy, disoriented, and even more sleepy than before beginning the nap. In order to attain maximum post-nap performance, it is critical that a power nap be limited to the beginning of a sleep cycle, specifically sleep stages I and II.
Scientific experiments (see Benefits section below) and anecdotal evidence suggest that an average power nap duration of around 15–30 minutes is most effective. Any more time, and the body enters into its usual sleep cycle. People who regularly take power naps may develop a good idea of what duration works best for them, as well as what tools, environment, position, and associated factors help induce the best results. Others may prefer to take power naps regularly even if their schedules allow a full night's sleep. Mitsuo Hayashi, PhD and Tadao Hori, PhD have demonstrated that a nap improves mental performance even after a full night's sleep. New sleep sensors and sleep timers available on several mobile devices allow advocates of power naps to sleep for exactly as long as they'd like to.
study led by David F. Dinges
, professor at the University of Pennsylvania School of Medicine
, found that naps can improve certain memory functions and that long naps are better than short ones. In that NASA study, volunteers spent several days living on one of 18 different sleep schedules, all in a laboratory setting. To measure the effectiveness of the naps, tests probing memory, alertness, response time, and other cognitive skills were used.
The National Institute of Mental Health
funded a team of doctors, led by Alan Hobson, MD, Robert Stickgold
, PhD, and colleagues at Harvard University
for a study which showed that a midday snooze reverses information overload
. Reporting in Nature Neuroscience
, Sara Mednick
, PhD, Stickgold and colleagues also demonstrated that "burnout" irritation, frustration and poorer performance on a mental task can set in as a day of training wears on. This study also proved that, in some cases, napping could even boost performance to an individual's top levels. The NIMH team wrote "The bottom line is: we should stop feeling guilty about taking that 'power nap' at work."
Sleep
Sleep is a naturally recurring state characterized by reduced or absent consciousness, relatively suspended sensory activity, and inactivity of nearly all voluntary muscles. It is distinguished from quiet wakefulness by a decreased ability to react to stimuli, and is more easily reversible than...
which terminates before the occurrence of deep sleep or slow-wave sleep
Slow-wave sleep
Slow-wave sleep , often referred to as deep sleep, consists of stages 3 and 4 of non-rapid eye movement sleep, according to the Rechtschaffen & Kales standard of 1968. As of 2008, the American Academy of Sleep Medicine has discontinued the use of stage 4, such that the previous stages 3 and 4 now...
(SWS), intended to quickly revitalize the subject. The expression was coined by Cornell University
Cornell University
Cornell University is an Ivy League university located in Ithaca, New York, United States. It is a private land-grant university, receiving annual funding from the State of New York for certain educational missions...
social psychologist James Maas
James Maas
James Maas is an American social psychologist, professor at Cornell University, and Stephen H. Weiss Presidential Fellow. He is best known for his work in the field of sleep research, specifically the relationship between sleep and performance. He coined the term "power nap" and wrote the...
.
Characteristics
The power nap is thought to maximize the benefits of sleep versus time. It is used to supplement normal sleep, especially when a sleeper has accumulated a sleep deficitSleep debt
Sleep debt or sleep deficit is the cumulative effect of not getting enough sleep. A large sleep debt may lead to mental and/or physical fatigue....
.
Various durations are recommended for power naps, which are very short compared to regular sleep. The short duration of a power nap is designed to prevent nappers from sleeping so long that they enter a normal sleep cycle without being able to complete it. Entering a normal sleep cycle, but failing to complete it, can result in a phenomenon known as sleep inertia
Sleep inertia
Sleep inertia is a physiological state characterised by a decline in motor dexterity and a subjective feeling of grogginess immediately following an abrupt awakening. The impaired alertness may interfere with the ability to perform mental or physical tasks...
, where one feels groggy, disoriented, and even more sleepy than before beginning the nap. In order to attain maximum post-nap performance, it is critical that a power nap be limited to the beginning of a sleep cycle, specifically sleep stages I and II.
Scientific experiments (see Benefits section below) and anecdotal evidence suggest that an average power nap duration of around 15–30 minutes is most effective. Any more time, and the body enters into its usual sleep cycle. People who regularly take power naps may develop a good idea of what duration works best for them, as well as what tools, environment, position, and associated factors help induce the best results. Others may prefer to take power naps regularly even if their schedules allow a full night's sleep. Mitsuo Hayashi, PhD and Tadao Hori, PhD have demonstrated that a nap improves mental performance even after a full night's sleep. New sleep sensors and sleep timers available on several mobile devices allow advocates of power naps to sleep for exactly as long as they'd like to.
Benefits
For several years scientists have been investigating the benefits of napping, both the 20-minute power nap and much longer sleep durations as long as 1–2 hours. Performance across a wide range of cognitive processes has been tested. Studies demonstrate that naps are as good as a night of sleep for some types of memory tasks. A NASANASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
study led by David F. Dinges
David F. Dinges
David F. Dinges 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...
, professor at the University of Pennsylvania School of Medicine
University of Pennsylvania School of Medicine
The Perelman School of Medicine , formerly the University of Pennsylvania School of Medicine, was founded in 1765, making it the oldest American medical school. As part of the University of Pennsylvania, it is located in the University City section of Philadelphia, Pennsylvania. It is widely...
, found that naps can improve certain memory functions and that long naps are better than short ones. In that NASA study, volunteers spent several days living on one of 18 different sleep schedules, all in a laboratory setting. To measure the effectiveness of the naps, tests probing memory, alertness, response time, and other cognitive skills were used.
The National Institute of Mental Health
National Institute of Mental Health
The National Institute of Mental Health is one of 27 institutes and centers that make up the National Institutes of Health...
funded a team of doctors, led by Alan Hobson, MD, Robert Stickgold
Robert Stickgold
Robert Stickgold is an Associate Professor of Psychiatry at Harvard Medical School and Beth Israel Deaconess Medical Center. A preeminent sleep researcher, Dr. Stickgold has dedicated his life to understanding the relationship between sleep and learning. He is also a very active educator...
, PhD, and colleagues at Harvard University
Harvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...
for a study which showed that a midday snooze reverses information overload
Information overload
"Information overload" is a term popularized by Alvin Toffler in his bestselling 1970 book Future Shock. It refers to the difficulty a person can have understanding an issue and making decisions that can be caused by the presence of too much information...
. Reporting in Nature Neuroscience
Nature Neuroscience
Nature Neuroscience is a monthly scientific journal published by Nature Publishing Group. Its focus is original research papers relating specifically to neuroscience and was established in May 1998. According to the Journal Citation Reports, Nature Neuroscience has a 2009 impact factor of 14.345,...
, Sara Mednick
Sara Mednick
Sara C. Mednick is a sleep researcher at the University of California, San Diego. Her research focuses on the relationship between napping and performance. She is the author of several papers and a mass market book, Take a Nap! Change Your Life....
, PhD, Stickgold and colleagues also demonstrated that "burnout" irritation, frustration and poorer performance on a mental task can set in as a day of training wears on. This study also proved that, in some cases, napping could even boost performance to an individual's top levels. The NIMH team wrote "The bottom line is: we should stop feeling guilty about taking that 'power nap' at work."