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, [1] 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 or as a means to supplement before or after loss of sleep. 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. There are multiple different types of naps depending on what the user's desired outcome may be or time constraints they may have, and 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, and naps have been shown to have various cognitive, physical, and psychosocial benefits. [2] [1]

Contents

Types of naps

Agricultural workers napping on the flax they harvested The Women's Land Army in Britain, 1915-1918 Q30909.jpg
Agricultural workers napping on the flax they harvested

Naps can be categorized based on their purpose and duration [3]

Purpose classifications

Duration classifications

Napping practices can be categorized based on duration, each offering distinct benefits and considerations:

  1. Micro nap (2–5 minutes): Extremely short naps lasting 2 to 5 minutes can enhance alertness and reduce fatigue while staying in the light sleep stages. Micro naps should not be confused with microsleeps, which are short lapses in wakefulness that occur while a person is attempting to stay awake and can be dangerous for the individual and people around them if not addressed quickly. [10]
  2. Power nap (10–30 minutes): Power naps typically last between 10 and 30 minutes and are designed to improve alertness and performance without the grogginess associated with deeper sleep stages. [11] The power nap is meant to maximize the benefits of sleep relative to time. It supplements normal sleep, especially when a sleeper has accumulated a sleep deficit. The greater the sleep deficit, the more effective the nap. [12]
  3. NASA nap (26 minutes): Based on research by NASA, a 26-minute nap has been shown to enhance alertness by 54% and performance by 34% among pilots and astronauts. [13]
  4. Slow-wave sleep nap (30–60 minutes): Naps lasting 30 to 60 minutes allow the body to enter slow-wave sleep, which is beneficial for decision-making skills and memorization. [14] However, waking up during this phase may result in increased sleep inertia.
  5. Full sleep cycle nap (90 minutes): A 90-minute nap typically encompasses a full sleep cycle, including light sleep, deep sleep, and REM sleep. This duration can enhance procedural memory and creativity and usually avoids sleep inertia, as the napper completes the full cycle. [15]

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. [16]

Benefits to napping

Learning and memory

Research suggests that shorter, habitual naps after instruction offer the most benefits to learning. [17] [18] 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. [19] Napping enhances alertness in young adults and adolescents during afternoons’ performances, which affect efficiency. [20] 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. [21]

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. [22] [18]

Cognitive capacity

In adults, a causal association has been found between habitual daytime napping and larger brain volume. [23] Brain volume normally declines with age, and is associated with neurodegenerative disease. [23] Earlier studies have shown benefits of napping for cognitive performance for healthy adults. [23]

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. [24] Twenty- to thirty-minute naps are recommended for adults, while young children and elderly people may need longer naps. [25] [26] Research, on the other hand, has shown that the benefits of napping depend on sleep onset and sleep phases rather than time and duration. [27]

Prescribed napping

It has been shown that excessive daytime sleepiness (EDS) can be improved by prescribed napping in narcolepsy. [28] Apart from narcolepsy, it has not been demonstrated that naps are beneficial for EDS in other sleep disorders. [28] For idiopathic hypersomnia, patients typically experience sleep inertia and are unrefreshed after napping. [29]

For healthy individuals in need of cognitive or emotional improvement, prescribed naps may be beneficial. [30] However, excessive napping, especially in adults with other health conditions, may be linked with negative outcomes and should be approached holistically and with caution. [30]

Negative effects of napping

Sleep inertia

The state of grogginess, impaired cognition and disorientation experienced when awakening from sleep is known as sleep inertia. [31] This state reduces the speed of cognitive tasks but has no effects on the accuracy of task performance. [28] The effects of sleep inertia rarely last longer than 30 minutes in the absence of prior sleep deprivation. [32]

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. [33] 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. [33]

Habitual naps are also an indicator of neurological degradation such as dementia in the elderly, as reduction in brain function causes more sleepiness. [34]

Naps across the lifespan

The need and benefits of napping vary across different age groups since sleep patterns and requirements across a person’s lifespan vary with time. [35]

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. [41] Sleep inertia is less intense after short naps. [42] Sleep latency is shorter when a nap is taken between 3 and 5 pm, compared with a nap taken between 7 and 9 pm. [43]

According to The Sleep Foundation, Psychology Today and Harvard Health Publishing, these are the best practices for napping: [25] [44] [26]

See also

References

  1. 1 2 Lovato, Nicole; Lack, Leon (2010). "The effects of napping on cognitive functioning". Progress in Brain Research. Vol. 185. Elsevier. pp. 155–166. doi:10.1016/b978-0-444-53702-7.00009-9. ISBN   978-0-444-53702-7 . Retrieved 8 April 2025. Naps (brief sleeps) are a global and highly prevalent phenomenon
  2. ↑ Rosekind MR, Smith RM, Miller DL, Co EL, Gregory, Webbon LL, et al. (December 1995). "Alertness management: strategic naps in operational settings". Journal of Sleep Research. 4 (S2): 62–66. doi: 10.1111/j.1365-2869.1995.tb00229.x . PMID   10607214. S2CID   23583942.
  3. ↑ "What Are the Different Types of Naps?". Sleep Doctor. 13 December 2022. Archived from the original on 19 January 2025. Retrieved 16 March 2025.
  4. ↑ Caldwell, John A.; Mallis, Melissa M.; Caldwell, J. Lynn; Paul, Michel A.; Miller, James C.; Neri, David F.; Aerospace Medical Association Fatigue Countermeasures Subcommittee of the Aerospace Human Factors Committee (January 2009). "Fatigue countermeasures in aviation". Aviation, Space, and Environmental Medicine. 80 (1): 29–59. doi:10.3357/asem.2435.2009. ISSN   0095-6562. PMID   19180856.
  5. ↑ Sieberichs, Sebastian; Kluge, Annette (September 2018). "Effects of In-Flight Countermeasures to Mitigate Fatigue Risks in Aviation" . Aviation Psychology and Applied Human Factors. 8 (2): 86–92. doi:10.1027/2192-0923/a000143. ISSN   2192-0923.
  6. ↑ Vizmanos, Barbara; Cascales, Ana Isabel; Rodríguez-Martín, María; Salmerón, Diego; Morales, Eva; Aragón-Alonso, Aurora; Scheer, Frank A. J. L.; Garaulet, Marta (2023). "Lifestyle mediators of associations among siestas, obesity, and metabolic health". Obesity. 31 (5): 1227–1239. doi: 10.1002/oby.23765 . ISSN   1930-739X. PMID   37140401.
  7. ↑ Reyner, L. A.; Horne, J. A. (November 1997). "Suppression of sleepiness in drivers: combination of caffeine with a short nap". Psychophysiology. 34 (6): 721–725. doi:10.1111/j.1469-8986.1997.tb02148.x. ISSN   0048-5772. PMID   9401427.
  8. ↑ Lange, Tanja; Dimitrov, Stoyan; Born, Jan (April 2010). "Effects of sleep and circadian rhythm on the human immune system". Annals of the New York Academy of Sciences. 1193 (1): 48–59. Bibcode:2010NYASA1193...48L. doi:10.1111/j.1749-6632.2009.05300.x. ISSN   1749-6632. PMID   20398008.
  9. ↑ Besedovsky, Luciana; Lange, Tanja; Born, Jan (January 2012). "Sleep and immune function". Pflügers Archiv: European Journal of Physiology. 463 (1): 121–137. doi:10.1007/s00424-011-1044-0. ISSN   1432-2013. PMC   3256323 . PMID   22071480.
  10. ↑ thensf (30 October 2021). "What is Microsleep?". National Sleep Foundation. Retrieved 17 March 2025.
  11. ↑ Lastella, Michele; Halson, Shona L.; Vitale, Jacopo A.; Memon, Aamir R.; Vincent, Grace E. (24 June 2021). "To Nap or Not to Nap? A Systematic Review Evaluating Napping Behavior in Athletes and the Impact on Various Measures of Athletic Performance". Nature and Science of Sleep. 13: 841–862. doi: 10.2147/NSS.S315556 . PMC   8238550 . PMID   34194254.
  12. ↑ "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.
  13. ↑ Rosekind, Mark R.; Graeber, R. Curtis; Dinges, David F.; Connell, Linda J.; Rountree, Michael S.; Spinweber, Cheryl L.; Gillen, Kelly A. (1 September 1994). "Crew factors in flight operations 9: Effects of planned cockpit rest on crew performance and alertness in long-haul operations".{{cite journal}}: Cite journal requires |journal= (help)
  14. ↑ Stepan, Michelle E.; Altmann, Erik M.; Fenn, Kimberly M. (12 November 2021). "Slow-wave sleep during a brief nap is related to reduced cognitive deficits during sleep deprivation". Sleep. 44 (11): zsab152. doi:10.1093/sleep/zsab152. ISSN   1550-9109. PMC   8598175 . PMID   34156468.{{cite journal}}: CS1 maint: article number as page number (link)
  15. ↑ Patel, Aakash K.; Reddy, Vamsi; Shumway, Karlie R.; Araujo, John F. (2025), "Physiology, Sleep Stages", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID   30252388 , retrieved 17 March 2025
  16. ↑ 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.
  17. ↑ Lemos N, Weissheimer J, Ribeiro S (3 June 2014). "Naps in school can enhance the duration of declarative memories learned by adolescents". Frontiers in Systems Neuroscience. 8: 103. doi: 10.3389/fnsys.2014.00103 . PMC   4042263 . PMID   24917794.
  18. 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.
  19. ↑ Takahashi M, Nakata A, Haratani T, Ogawa Y, Arito H (July 2004). "Post-lunch nap as a worksite intervention to promote alertness on the job". Ergonomics. 47 (9): 1003–1013. doi:10.1080/00140130410001686320. PMID   15204275. S2CID   37556310.
  20. ↑ Takahashi M, Fukuda H, Arito H (July 1998). "Brief naps during post-lunch rest: effects on alertness, performance, and autonomic balance". European Journal of Applied Physiology and Occupational Physiology. 78 (2): 93–98. doi:10.1007/s004210050392. PMID   9694306. S2CID   2601267.
  21. ↑ Tietzel AJ, Lack LC (September 2002). "The recuperative value of brief and ultra-brief naps on alertness and cognitive performance". Journal of Sleep Research. 11 (3): 213–218. doi:10.1046/j.1365-2869.2002.00299.x. PMID   12220317. S2CID   22706866.
  22. ↑ Tucker MA, Hirota Y, Wamsley EJ, Lau H, Chaklader A, Fishbein W (September 2006). "A daytime nap containing solely non-REM sleep enhances declarative but not procedural memory". Neurobiology of Learning and Memory. 86 (2): 241–247. doi:10.1016/j.nlm.2006.03.005. PMID   16647282. S2CID   17606945.
  23. 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.
  24. ↑ Leong, Ruth L F; Lau, TeYang; Dicom, Andrew R; Teo, Teck Boon; Ong, Ju Lynn; Chee, Michael W L (12 April 2023). "Influence of mid-afternoon nap duration and sleep parameters on memory encoding, mood, processing speed, and vigilance". Sleep. 46 (4). doi:10.1093/sleep/zsad025. ISSN   0161-8105. PMC   10091091 . PMID   36775965.
  25. 1 2 "Napping May Not Be Such a No-No". Harvard Health. 1 November 2009. Retrieved 18 February 2023.
  26. 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.
  27. ↑ 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.
  28. 1 2 3 Takahashi M (June 2003). "The role of prescribed napping in sleep medicine". Sleep Medicine Reviews. 7 (3): 227–35. doi:10.1053/smrv.2002.0241. PMID   12927122.
  29. ↑ Choo KL, Guilleminault C (March 1998). "Narcolepsy and idiopathic hypersomnolence". Clinics in Chest Medicine. 19 (1): 169–81. doi: 10.1016/s0272-5231(05)70440-8 . PMID   9554226.
  30. 1 2 Mantua, Janna; Spencer, Rebecca M.C. (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.
  31. ↑ 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.
  32. ↑ Tassi P, Muzet A (August 2000). "Sleep inertia". Sleep Medicine Reviews. 4 (4): 341–353. doi:10.1053/smrv.2000.0098. PMID   12531174.
  33. 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. Bibcode:2016NatSR...638075Y. doi:10.1038/srep38075. PMC   5133463 . PMID   27909305.
  34. ↑ 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.
  35. ↑ Simon, Katharine C.; Cadle, Chelsea; Shuster, Alessandra E.; Malerba, Paola (5 February 2025). "Sleep Across the Lifespan: A Neurobehavioral Perspective". Current Sleep Medicine Reports. 11 (1): 7. doi: 10.1007/s40675-025-00322-2 . ISSN   2198-6401.
  36. ↑ Colrain, Ian M.; Baker, Fiona C. (March 2011). "Changes in Sleep as a Function of Adolescent Development". Neuropsychology Review. 21 (1): 5–21. doi:10.1007/s11065-010-9155-5. ISSN   1040-7308. PMC   7543715 . PMID   21225346.
  37. ↑ Bruce, Ellen S; Lunt, Laura; McDonagh, Janet E (October 2017). "Sleep in adolescents and young adults". Clinical Medicine. 17 (5): 424–428. doi:10.7861/clinmedicine.17-5-424. PMC   6301929 . PMID   28974591.
  38. ↑ Kim, Minjung; Um, Yoo-Hyun; Kim, Tae-Won; Kim, Sung-Min; Seo, Ho-Jun; Jeong, Jong-Hyun; Lee, Jihyung; Kim, Suhyung; Cho, In Hee; Kim, Suk-Young; Hong, Seung-Chul (31 December 2021). "Association Between Age and Sleep Quality: Findings From a Community Health Survey". Sleep Medicine Research. 12 (2): 155–160. doi: 10.17241/smr.2021.01158 . ISSN   2093-9175.
  39. ↑ Souabni, Maher; Souabni, Mehdi J.; Hammouda, Omar; Romdhani, Mohamed; Trabelsi, Khaled; Ammar, Achraf; Driss, Tarak (21 October 2022). "Benefits and risks of napping in older adults: A systematic review". Frontiers in Aging Neuroscience. 14. doi: 10.3389/fnagi.2022.1000707 . ISSN   1663-4365. PMC   9634571 . PMID   36337699.
  40. ↑ Casagrande, Maria; Forte, Giuseppe; Favieri, Francesca; Corbo, Ilaria (11 July 2022). "Sleep Quality and Aging: A Systematic Review on Healthy Older People, Mild Cognitive Impairment and Alzheimer's Disease". International Journal of Environmental Research and Public Health. 19 (14): 8457. doi: 10.3390/ijerph19148457 . ISSN   1660-4601. PMC   9325170 . PMID   35886309.
  41. ↑ 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.
  42. ↑ 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.
  43. ↑ 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.{{cite journal}}: CS1 maint: article number as page number (link)
  44. ↑ Andrews LW (5 June 2010). "Ultimate Napping: A How-To Guide". Psychology Today. Retrieved 18 February 2023.
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