A power nap or cat nap is a short

sleep Sleep is a state of reduced mental and physical activity in which consciousness is altered and certain Sensory nervous system, sensory activity is inhibited. During sleep, there is a marked decrease in muscle activity and interactions with th ...

that terminates before deep sleep (

slow-wave sleep Slow-wave sleep (SWS), often referred to as deep sleep, is the third stage of non-rapid eye movement sleep (NREM), where electroencephalography activity is characterised by slow delta waves. Slow-wave sleep usually lasts between 70 and 90 mi ...

; SWS). A power nap is intended to quickly revitalize the sleeper. A power nap combined with consuming caffeine is called a stimulant nap, coffee nap, caffeine nap, or nappuccino.

Characteristics

A power nap, also known as a Stage 2 nap, is a short slumber of 20 minutes or less which terminates before the occurrence of deep

, intended to quickly revitalize the napper. The expression "power nap" was coined by

Cornell University Cornell University is a Private university, private Ivy League research university based in Ithaca, New York, United States. The university was co-founded by American philanthropist Ezra Cornell and historian and educator Andrew Dickson W ...

social psychologist Social psychology is the methodical study of how thoughts, feelings, and behaviors are influenced by the actual, imagined, or implied presence of others. Although studying many of the same substantive topics as its counterpart in the field of ...

James Maas. The 20-minute nap increases alertness and motor skills. Various durations may be recommended for power naps, which are short compared to regular sleep. The short duration prevents nappers from sleeping so long that they enter the slow wave portion of the normal sleep cycle without being able to complete the cycle. Entering deep, slow-wave sleep and failing to complete the normal sleep cycle, can result in a phenomenon known as

sleep inertia Sleep is a state of reduced mental and physical activity in which consciousness is altered and certain sensory activity is inhibited. During sleep, there is a marked decrease in muscle activity and interactions with the surrounding environme ...

, where one feels groggy, disoriented, and even sleepier than before beginning the nap. In order to attain optimal post-nap performance, a Stage 2 nap must be limited to the beginning of a sleep cycle, specifically sleep stages N1 and N2, typically 18–25 minutes. Experimental confirmation of the benefits of this brief nap comes from a

Flinders University Flinders University, established as The Flinders University of South Australia is a public university, public research university based in Adelaide, South Australia, with a footprint extending across a number of locations in South Australia and ...

study in

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in which 5, 10, 20, or 30-minute periods of sleep were given. The greatest immediate improvement in measures of alertness and cognitive performance came after the 10 minutes of sleep. The 20 and 30-minute periods of sleep showed evidence of sleep inertia immediately after the naps and improvements in alertness more than 30 minutes later, but not to a greater level than after the 10 minutes of sleep. Power naps are effective even when schedules allow a full night's sleep.

Research

Potential benefits

Power naps intend to restore

alertness Alertness is a state of active attention characterized by high sensory awareness. Someone who is alert is vigilant and promptly meets danger or emergency, or is quick to perceive and act. Alertness is a psychological and physiological state. Lac ...

, performance, and learning ability. A nap may also reverse the hormonal impact of a night of poor sleep or reverse the damage of

sleep deprivation Sleep deprivation, also known as sleep insufficiency or sleeplessness, is the condition of not having adequate duration and/or quality of sleep to support decent alertness, performance, and health. It can be either Chronic (medicine), chronic ...

. A

University of Düsseldorf A university () is an institution of tertiary education and research which awards academic degrees in several academic disciplines. ''University'' is derived from the Latin phrase , which roughly means "community of teachers and scholars". Univ ...

study found superior memory recall once a person had reached 6 minutes of sleep, suggesting that the onset of sleep may initiate active memory processes of consolidation which—once triggered—remains effective even if sleep is terminated. According to

clinical studies Clinical trials are prospective biomedical or behavioral research studies on human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel vaccines, drugs, dietar ...

among men and women, power nappers of any frequency or duration had a significantly lower mortality ratio due to

heart disease Cardiovascular disease (CVD) is any disease involving the heart or blood vessels. CVDs constitute a class of diseases that includes: coronary artery diseases (e.g. angina pectoris, angina, myocardial infarction, heart attack), heart failure, ...

than those not napping. Specifically, those occasionally napping had a 12% lower

coronary Coronary () may, as shorthand in English, be used to mean: * Coronary circulation, the system of arteries and veins in mammals ** Coronary artery disease ** Coronary occlusion ** A myocardial infarction, a heart attack As adjective * Referring to ...

mortality, whereas those systematically napping had a 37% lower coronary mortality. A

study of individuals restricted to only five hours of sleep per night found a 10-minute nap was overall the most recuperative nap duration of various nap lengths they examined (lengths of 0 min, 5 min, 10 min, 20 min, and 30 minutes): the 5-minute nap produced few benefits in comparison with the no-nap control; the 10-minute nap produced immediate improvements in all outcome measures (including

sleep onset latency In sleep science, sleep onset latency (SOL) is the length of time that it takes to accomplish the transition from full wakefulness to sleep, normally to the lightest of the non-REM sleep stages. Sleep latency studies Pioneering Stanford Univers ...

, subjective

sleepiness Somnolence (alternatively sleepiness or drowsiness) is a state of strong desire for sleep, or sleeping for unusually long periods (compare hypersomnia). It has distinct meanings and causes. It can refer to the usual state preceding falling asleep ...

, fatigue, vigor, and cognitive performance), with some of these benefits maintained for as long as 155 minutes; the 20-minute nap was associated with improvements emerging 35 minutes after napping and lasting up to 125 minutes after napping; and the 30-minute nap produced a period of impaired alertness and performance immediately after napping, indicative of sleep inertia, followed by improvements lasting up to 155 minutes after the nap. The

NASA Ames The Ames Research Center (ARC), also known as NASA Ames, is a major NASA research center at Moffett Federal Airfield in California's Silicon Valley. It was founded in 1939 as the second National Advisory Committee for Aeronautics (NACA) laborat ...

Fatigue Countermeasures Group studied the effects of sleep loss and

jet lag Jet lag is a temporary physiological condition that occurs when a person's circadian rhythm is out of sync with the time zone they are in, and is a typical result from travelling rapidly across multiple time zones (east–west or west–east). ...

, and conducts training to counter these effects. A major fatigue countermeasures recommendation consists of a 40-minute nap ("NASA nap") which empirically showed to improve flight crew performance and alertness with a 22% statistical risk of entering SWS. For several years, scientists have been investigating the benefits of napping, both the 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

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

study led by David F. Dinges, professor at the

University of Pennsylvania School of Medicine The Perelman School of Medicine (commonly known as Penn Med) is the medical school of the University of Pennsylvania, a Private university, private, Ivy League research university located in Philadelphia. Founded in 1765, the Perelman School of M ...

, found that naps can improve certain memory functions. 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. Power Napping Enablers and sleep timers allow properly timed power napping. One study showed that a midday snooze reverses

information overload Information overload (also known as infobesity, infoxication, or information anxiety) is the difficulty in understanding an issue and Decision making, effectively making decisions when one has too much information (TMI) about that issue, and is ...

. Reporting in ''

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. The chief editor is Shari Wiseman. According ...

'', 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." The Centers for Disease Control and Prevention studied the effects of socioeconomic status on short sleep durations. In this 2007-2008 CDCP study, 4,850 National Health and Nutrition Examination Survey (NHANES) produced self-reported sleep durations. It was suggested through this study that individuals with minority status and a lower ranking in socioeconomic position are more inclined to have shorter self-reported slee
durations

Potential risks and detriments

Longer and more frequent daytime naps appeared to be associated with a higher risk of Alzheimer's dementia in a study that tracked 1401 older people over 14 years. Links have also been proposed between these types of naps and

cardiovascular disease Cardiovascular disease (CVD) is any disease involving the heart or blood vessels. CVDs constitute a class of diseases that includes: coronary artery diseases (e.g. angina, heart attack), heart failure, hypertensive heart disease, rheumati ...

, though the evidence is largely inconclusive. A series of studies by the medical journal

Sleep Sleep is a state of reduced mental and physical activity in which consciousness is altered and certain Sensory nervous system, sensory activity is inhibited. During sleep, there is a marked decrease in muscle activity and interactions with th ...

demonstrated that people who nap for an hour or more a day had 1.82 times the rate of cardiovascular disease than people who didn't nap.

Stimulant nap

A stimulant nap is a brief period of sleep of around 15 minutes, preceded by consuming a

caffeinated Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class and is the most commonly consumed psychoactive substance globally. It is mainly used for its eugeroic (wakefulness promoting), ergogenic (physical performance-e ...

drink or another stimulant. It may combat daytime drowsiness more effectively than napping or drinking coffee alone. A stimulant nap is more effective than regular naps in improving post-nap alertness and cognitive functioning. In a driving simulator and a series of studies, Horne and Reyner investigated the effects of cold air, radio, a break with no nap, a nap, caffeine pill vs. placebo and a short nap preceded by caffeine on mildly sleep-deprived subjects. A nap with caffeine was by far the most effective in reducing driving accidents and subjective sleepiness as it helps the body get rid of the sleep-inducing chemical compound

adenosine Adenosine (symbol A) is an organic compound that occurs widely in nature in the form of diverse derivatives. The molecule consists of an adenine attached to a ribose via a β-N9- glycosidic bond. Adenosine is one of the four nucleoside build ...

. Caffeine in coffee takes up to half an hour to have an alerting effect, hence "a short (<15min) nap will not be compromised if it is taken immediately after the coffee." One account suggested that it was like a "double shot of energy" from the stimulating boost from caffeine plus better alertness from napping. This procedure has been studied on sleep-deprived humans given the task of driving a motor vehicle afterwards, although it has not been studied on elderly populations.

Nap rooms and tech aided naps

Some companies have nap rooms to allow employees to take power naps. This may be in a form of a nap room with a recliner, or chairs specially designed for power napping installed in a designated area. Companies with nap rooms say that employees are happier and become more productive at work. Similar nap rooms and stations also exist in

higher education Tertiary education (higher education, or post-secondary education) is the educational level following the completion of secondary education. The World Bank defines tertiary education as including universities, colleges, and vocational schools ...

institutions. Many colleges and universities provide napping furnitures such as

cots COTS may refer to: * Commercial off-the-shelf, products that are commercially available and can be bought "as is" * Commercial Orbital Transportation Services, a NASA program for delivery to the International Space Station by private companies * ...

and

beanbag A bean bag (also beanbag) is a sealed bag containing dried beans, Polyvinyl chloride, PVC pellets, expanded polystyrene, or expanded polypropylene. The bags are commonly used for throwing games, but they have various other applications. Games * ...

s in libraries for students to take naps after long periods of study. At least one university has a nap room set up in a

gym A gym, short for gymnasium (: gymnasiums or gymnasia), is an indoor venue for exercise and sports. The word is derived from the ancient Greek term " gymnasion". They are commonly found in athletic and fitness centres, and as activity and learn ...

. Some

medical school A medical school is a tertiary educational institution, professional school, or forms a part of such an institution, that teaches medicine, and awards a professional degree for physicians. Such medical degrees include the Bachelor of Medicine, ...

s also set up nap rooms at

teaching hospital A teaching hospital or university hospital is a hospital or medical center that provides medical education and training to future and current health professionals. Teaching hospitals are almost always affiliated with one or more universities a ...

s. The nap rooms may include sleeping pods or cots, white noise machines, and antimicrobial pillows. In Barcelona, there is a café called Nappuccino(16 March 201
"Télématin France 2 TV". FRANCE 2 TV 2h27min
/ref> that implements custom-built napping pods inside the café. A more portable aid is a nap timer app. Apps have various features including aided sounds, nap history and pattern tracking and daily reminders that make it easier to take naps.

References

External links

Boston Globe article on power naps

University of Miami : "Sleep, Napping and the Brain -The Power of Napping"
YouTube {{DEFAULTSORT:Power Nap Sleep sv:Sömn#Tupplur