Nap

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A man napping in a hammock, on a patio in Costa Rica Hammock nap on patio.jpg
A man napping in a hammock, on a patio in Costa Rica

A nap is a short period of sleep, typically taken during daytime hours as an adjunct to the usual nocturnal sleep period. Naps are most often taken as a response to drowsiness during waking hours. A nap is a form of biphasic or polyphasic sleep, where the latter terms also include longer periods of sleep in addition to one period. For years, scientists have been investigating the benefits of napping, including the 30-minute nap as well as sleep durations of 1–2 hours. Performance across a wide range of cognitive processes has been tested. [1]

Contents

Benefits

Sara Mednick conducted a study experimenting on the effects of napping, caffeine, and a placebo. Her results showed that a 60–90-minute nap is more effective than caffeine in memory and cognition. [2]

Power nap

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 slow-wave sleep, intended to quickly revitalize the napper. The power nap is meant to maximize the benefits of sleep versus time. It is used to supplement normal sleep, especially when a sleeper has accumulated a sleep deficit. The greater the sleep deficit, the more effective the nap. [3]

Prescribed napping for sleep disorders

It has been shown that excessive daytime sleepiness (EDS) can be improved by prescribed napping in narcolepsy. [4] Apart from narcolepsy, it has not been demonstrated that naps are beneficial for EDS in other sleep disorders. [4]

Learning and memory

Research suggests that shorter, habitual naps after instruction offer the most benefits to learning. [5] [6] The benefits to alertness show no change based on duration of the nap for combating post-lunch dip, even for naps as short as 10 minutes. [7] Napping enhances alertness in young adults and adolescents during afternoons’ performances, which affect efficiency. [8] Additionally, pre-teens who nap regularly during the day demonstrate better sleep at night. In younger children, napping increased drowsiness even while improving memory recall. [9]

For students of all ages, napping during the school day showed benefits to reaction time and recall of declarative memory of new information, especially if the naps remain in slow-wave sleep, i.e. less than an hour in length. [10] [6]

Cognitive capacity

In adults, a causal association has been found between habitual daytime napping and larger brain volume. [11] Brain volume normally declines with age, and is associated with neurodegenerative disease. [11] Earlier studies have shown benefits of napping for cognitive performance for healthy adults. [11]

Alertness and fatigue

The circadian cycle plays a role in the rising demand for daytime naps: sleepiness rises towards the mid-afternoon, hence the best timing for naps is early afternoon. [12] [ citation not found ] Twenty- to thirty-minute naps are recommended for adults, while young children and elderly people may need longer naps. [13] [14] Research, on the other hand, has shown that the benefits of napping depend on sleep onset and sleep phases rather than time and duration. [15]

Negative effects

Sleep inertia

The state of grogginess, impaired cognition and disorientation experienced when awakening from sleep is known as sleep inertia. [16] This state reduces the speed of cognitive tasks but has no effects on the accuracy of task performance. [4] The effects of sleep inertia rarely last longer than 30 minutes in the absence of prior sleep deprivation. [17]

Potential health risks

A 2016 meta-analysis showed that there may be a correlation between habitual napping for more than an hour, and having an increased risk for cardiovascular disease, diabetes, metabolic syndrome or death. [18] There was no effect of napping for as long as 40 minutes per day, but a sharp increase in risk of disease occurred at longer nap times. No causal relationship was established: the link may be to do with people taking a longer nap in response to the pre-existence of other risk factors. [18]

Habitual naps are also an indicator of neurological degradation such as dementia in the elderly, as reduction in brain function causes more sleepiness. [19]

On sleep disorders

For idiopathic hypersomnia, patients typically experience sleep inertia and are unrefreshed after napping. [20]

Best practices

How long and when a person naps affects sleep inertia and sleep latency: a person is more likely to benefit in terms of those two points when they sleep moderately in the afternoon. According to research, the degree to which a person experiences sleep inertia differs in different durations of nap. Because sleep inertia is possibly resulting from awakening from slow-wave sleep, it is more likely to happen when one has a longer nap. [21] Sleep inertia is less intense after short naps. [22] Sleep latency is shorter when a nap is taken between 3 and 5 pm, compared with a nap taken between 7 and 9 pm. [23]

According to The Sleep Foundation, Psychology Today and Harvard Health Publishing, these are the best practices for napping: [13] [24] [14]

See also

Related Research Articles

<span class="mw-page-title-main">Sleep</span> Naturally recurring resting state of mind and body

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 environment. While sleep differs from wakefulness in terms of the ability to react to stimuli, it still involves active brain patterns, making it more reactive than a coma or disorders of consciousness.

<span class="mw-page-title-main">Sleep disorder</span> Medical disorder of a persons sleep patterns

A sleep disorder, or somnipathy, is a medical disorder of an individual's sleep patterns. Some sleep disorders are severe enough to interfere with normal physical, mental, social and emotional functioning. Sleep disorders are frequent and can have serious consequences on patients' health and quality of life. Polysomnography and actigraphy are tests commonly ordered for diagnosing sleep disorders.

<span class="mw-page-title-main">Stimulant</span> Drug that increases activity of central nervous system

Stimulants are a class of drugs that increase the activity of the brain. They are used for various purposes, such as enhancing alertness, attention, motivation, cognition, mood, and physical performance. Some of the most common stimulants are caffeine, nicotine, amphetamines, cocaine, methylphenidate, and modafinil.

<span class="mw-page-title-main">Power nap</span> Short sleep

A power nap or cat nap is a short sleep that terminates before deep sleep. A power nap is intended to quickly revitalize the sleeper.

Hypersomnia is a neurological disorder of excessive time spent sleeping or excessive sleepiness. It can have many possible causes and can cause distress and problems with functioning. In the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), hypersomnolence, of which there are several subtypes, appears under sleep-wake disorders.

Sleep inertia is a physiological state of impaired cognitive and sensory-motor performance that is present immediately after awakening. It persists during the transition of sleep to wakefulness, where an individual will experience feelings of drowsiness, disorientation and a decline in motor dexterity. Impairment from sleep inertia may take several hours to dissipate. In the majority of cases, morning sleep inertia is experienced for 15 to 30 minutes after waking.

<span class="mw-page-title-main">Slow-wave sleep</span> Period of sleep in humans and other animals

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.

Shift work sleep disorder (SWSD) is a circadian rhythm sleep disorder characterized by insomnia, excessive sleepiness, or both affecting people whose work hours overlap with the typical sleep period. Insomnia can be the difficulty to fall asleep or to wake up before the individual has slept enough. About 20% of the working population participates in shift work. SWSD commonly goes undiagnosed, so it's estimated that 10–40% of shift workers have SWSD. The excessive sleepiness appears when the individual has to be productive, awake and alert. Both symptoms are predominant in SWSD. There are numerous shift work schedules, and they may be permanent, intermittent, or rotating; consequently, the manifestations of SWSD are quite variable. Most people with different schedules than the ordinary one might have these symptoms but the difference is that SWSD is continual, long-term, and starts to interfere with the individual's life.

Excessive daytime sleepiness (EDS) is characterized by persistent sleepiness and often a general lack of energy, even during the day after apparently adequate or even prolonged nighttime sleep. EDS can be considered as a broad condition encompassing several sleep disorders where increased sleep is a symptom, or as a symptom of another underlying disorder like narcolepsy, circadian rhythm sleep disorder, sleep apnea or idiopathic hypersomnia.

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.

<span class="mw-page-title-main">Lisdexamfetamine</span> Central nervous system stimulant prodrug

Lisdexamfetamine, sold under the brand names Vyvanse and Elvanse among others, is a stimulant medication that is used medically to treat attention deficit hyperactivity disorder (ADHD) in children and adults, moderate-to-severe binge eating disorder in adults, and cognitive disengagement syndrome (CDS) in adults. Lisdexamfetamine is taken by mouth. Its effects generally begin within two hours and last for up to 14 hours.

Caffeine-induced sleep disorder is a psychiatric disorder that results from overconsumption of the stimulant caffeine. Caffeine is one of the most widely consumed psychoactive drugs: almost 90% of Americans in a survey consume some type of caffeine each day. "When caffeine is consumed immediately before bedtime or .... throughout the day, sleep onset may be delayed, total sleep time reduced, normal stages of sleep altered, and the quality of sleep decreased." Caffeine reduces slow-wave sleep in the early part of the sleep cycle and can reduce rapid eye movement sleep later in the cycle. Caffeine increases episodes of wakefulness, and high doses in the late evening can increase sleep onset latency. In elderly people, there is an association between use of medication containing caffeine and difficulty in falling asleep.

<span class="mw-page-title-main">Sleep deprivation</span> Condition of not having enough sleep

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 or acute and may vary widely in severity. All known animals sleep or exhibit some form of sleep behavior, and the importance of sleep is self-evident for humans, as nearly a third of a person's life is spent sleeping.

<span class="mw-page-title-main">Narcolepsy</span> Human sleep disorder

Narcolepsy is a chronic neurological disorder that impairs the ability to regulate sleep–wake cycles, and specifically impacts REM sleep. The pentad symptoms of narcolepsy include excessive daytime sleepiness (EDS), sleep related hallucinations, sleep paralysis, disturbed nocturnal sleep (DNS) and cataplexy. There are two recognized forms of narcolepsy, narcolepsy type 1 and type 2. Narcolepsy type 1 (NT1) can be clinically characterized by symptoms of EDS and cataplexy, and/or will have CSF orexin levels of less than 110 pg/ml. Cataplexy are transient episodes of aberrant tone, most typically loss of tone, that can be associated with strong emotion. In pediatric onset narcolepsy, active motor phenomena are not uncommon. Cataplexy may be mistaken for syncope, tic disorder or seizures. Narcolepsy type 2 (NT2) does not have features of cataplexy and CSF orexin levels are normal. Sleep related hallucinations, also known as hypnogogic and hypnopompic are vivid hallucinations that can be auditory, visual or tactile and may occur independent of or in combination with an inability to move. People with narcolepsy tend to sleep about the same number of hours per day as people without it, but the quality of sleep is typically compromised. Narcolepsy is a clinical syndrome of hypothalamic disorder, but the exact cause of narcolepsy is unknown, with potentially several causes. A leading consideration for the cause of narcolepsy type 1 is that it is an autoimmune disorder. Proposed pathophysiology as an autoimmune disease suggest antigen presentation by DQ0602 to specific CD4+ T cells resulting in CD8+ T-cell activation and consequent injury to orexin producing neurons. Familial trends of narcolepsy are suggested to be higher than previously appreciated. Familial risk of narcolepsy among first degree relatives is high. Relative risk for narcolepsy in a first degree relative has been reported to be 361.8. However, it is important to note that there is a spectrum of symptoms found in this study, including asymptomatic abnormal sleep test findings to significantly symptomatic.

<span class="mw-page-title-main">Effect of caffeine on memory</span>

Caffeine is a bitter, white crystalline xanthine alkaloid that acts as a psychoactive stimulant drug. It can have both positive and negative effects on different aspects of memory.

Idiopathic hypersomnia(IH) is a neurological disorder which is characterized primarily by excessive sleep and excessive daytime sleepiness (EDS). Idiopathic hypersomnia was first described by Bedrich Roth in 1976, and it can be divided into two forms: polysymptomatic and monosymptomatic. The condition typically becomes evident in early adulthood and most patients diagnosed with IH will have had the disorder for many years prior to their diagnosis. As of August 2021, an FDA-approved medication exists for IH called Xywav, which is oral solution of calcium, magnesium, potassium, and sodium oxybates; in addition to several off-label treatments (primarily FDA-approved narcolepsy medications).

The effects of sleep deprivation on cognitive performance are a broad range of impairments resulting from inadequate sleep, impacting attention, executive function and memory. An estimated 20% of adults or more have some form of sleep deprivation. It may come with insomnia or major depressive disorder, or indicate other mental disorders. The consequences can negatively affect the health, cognition, energy level and mood of a person and anyone around. It increases the risk of human error, especially with technology.

Neuroenhancement or cognitive enhancement is the experimental use of pharmacological or non-pharmacological methods intended to improve cognitive and affective abilities in healthy people who do not have a mental illness. Agents or methods of neuroenhancement are intended to affect cognitive, social, psychological, mood, or motor benefits beyond normal functioning.

<span class="mw-page-title-main">Sleep deprivation in higher education</span> Health issue in students

Sleep deprivation – the condition of not having enough sleep – is a common health issue for students in higher education. This issue has several underlying and negative consequences, but there are a few helpful improvements that students can make to reduce its frequency and severity.

Adolescent sleep is typically poor in duration and quality. Sleep duration and quality reduce to suboptimal levels, and sleep duration variability and latency increases during adolescence. Sleep recommendations suggest that adolescents should obtain 8–10 hours of sleep per night. Additionally, there is a shift in the body's circadian rhythm such that sleep and wake timings become later during adolescence. Technology, social factors, and physical development are thought to contribute to poor sleep during this time. Poor sleep duration and quality in adolescents has been linked with altered brain functioning and development, poor mental and physical health, as well as higher rates of disease and mortality. The concerns surrounding poor sleep during adolescence has garnered significant public attention, especially concerning policies related to school start times. Many evidences suggest that sleep contributes positively to attention, behavior, and academic achievement for adolescents.

References

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  2. ↑ Mednick SC, Cai DJ, Kanady J, Drummond SP (November 2008). "Comparing the benefits of caffeine, naps and placebo on verbal, motor and perceptual memory". Behavioural Brain Research. 193 (1): 79–86. doi:10.1016/j.bbr.2008.04.028. PMC   2603066 . PMID   18554731.
  3. ↑ "Temporal Placement of a Nap for Alertness: Contributions of Circadian Phase and Prior Wakefulness". Sleep. 1 July 1987. doi: 10.1093/sleep/10.4.313 . ISSN   1550-9109.
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  6. 1 2 Ji X, Li J, Liu J (February 2018). "The Relationship Between Midday Napping And Neurocognitive Function in Early Adolescents". Behavioral Sleep Medicine. 17 (5): 537–551. doi:10.1080/15402002.2018.1425868. PMC   6669094 . PMID   29388804.
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  11. 1 2 3 Paz V, Dashti HS, Garfield V (2023). "Is there an association between daytime napping, cognitive function, and brain volume? A Mendelian randomization study in the UK Biobank". Sleep Health . 9 (5): 786–793. doi:10.1016/j.sleh.2023.05.002. PMID   37344293.
  12. ↑ Stampi 1992 ; Bertisch as cited in Bilodeau 2021 .
  13. 1 2 "Napping May Not Be Such a No-No". Harvard Health. 1 November 2009. Retrieved 18 February 2023.
  14. 1 2 Chan OY, Phoon WH, Gan SL, Ngui SJ (October 1989). "Sleep-wake patterns and subjective sleep quality of day and night workers: interaction between napping and main sleep episodes". Sleep. 12 (5): 439–448. doi: 10.1093/sleep/12.5.439 . PMID   2799217.
  15. ↑ Jones BJ, Spencer RM (December 2020). "Role of Napping for Learning across the Lifespan". Current Sleep Medicine Reports. 6 (4): 290–297. doi:10.1007/s40675-020-00193-9. PMC   8011550 . PMID   33816064.
  16. ↑ Dinges DF (1990). "Are you awake? Cognitive performance and reverie during the hypnopompic state.". In Bootzin R, Kihlstrom J, Schacter D (eds.). Sleep and Cognition. Washington, DC: American Psychological Society. pp. 159–175. doi:10.1037/10499-012. ISBN   1-55798-083-7.
  17. ↑ Tassi P, Muzet A (August 2000). "Sleep inertia". Sleep Medicine Reviews. 4 (4): 341–353. doi:10.1053/smrv.2000.0098. PMID   12531174.
  18. 1 2 Yamada T, Shojima N, Yamauchi T, Kadowaki T (December 2016). "J-curve relation between daytime nap duration and type 2 diabetes or metabolic syndrome: A dose-response meta-analysis". Scientific Reports. 6 (1): 38075. doi:10.1038/srep38075. PMC   5133463 . PMID   27909305.
  19. ↑ Mantua J, Spencer RM (September 2017). "Exploring the nap paradox: are mid-day sleep bouts a friend or foe?". Sleep Medicine. 37: 88–97. doi:10.1016/j.sleep.2017.01.019. PMC   5598771 . PMID   28899546.
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  21. ↑ Milner CE, Cote KA (June 2009). "Benefits of napping in healthy adults: impact of nap length, time of day, age, and experience with napping". Journal of Sleep Research. 18 (2): 272–281. doi:10.1111/j.1365-2869.2008.00718.x. PMID   19645971. S2CID   22815227.
  22. ↑ Santos JS, Beijamini F, Louzada FM (28 July 2021). "Napping Behavior in Adolescents: Consensus, Dissents, and Recommendations". Sleep and Vigilance. 5 (2): 189–196. doi:10.1007/s41782-021-00155-3. ISSN   2510-2265. S2CID   237714078.
  23. ↑ Shrivastava D, Jung S, Saadat M, Sirohi R, Crewson K (January 2014). "How to interpret the results of a sleep study". Journal of Community Hospital Internal Medicine Perspectives. 4 (5): 24983. doi:10.3402/jchimp.v4.24983. PMC   4246141 . PMID   25432643.
  24. ↑ Andrews LW (5 June 2010). "Ultimate Napping: A How-To Guide". Psychology Today. Retrieved 18 February 2023.
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