Sleep deprivation

==Effects and consequences==
[[File:Effects of sleep deprivation.svg|thumb|300px|Main health effects of sleep deprivation]]

===The brain===

==== Temporary ====
One study suggested, based on neuroimaging, that 35 hours of total sleep deprivation in healthy controls negatively affected the brain's ability to put an emotional event into the proper perspective and make a controlled, suitable response to the event.<ref>{{cite journal | vauthors = Yoo SS, Gujar N, Hu P, Jolesz FA, Walker MP | title = The human emotional brain without sleep--a prefrontal amygdala disconnect | journal = Current Biology | volume = 17 | issue = 20 | pages = R877–R878 | date = October 2007 | pmid = 17956744 | doi = 10.1016/j.cub.2007.08.007 | s2cid = 9008816 | doi-access = free | bibcode = 2007CBio...17.R877Y }}</ref>

According to the latest research, lack of sleep may cause more harm than previously thought and may lead to the permanent loss of brain cells.<ref>{{Cite web |date=2014-03-21 |title=最新研究：睡眠不足会永久损伤脑细胞 | trans-title = Latest research: Lack of sleep can permanently damage brain cells |url=https://www.bbc.com/zhongwen/simp/science/2014/03/140321_lost_sleep |access-date=2023-12-05 |website=BBC News 中文 (Chinese) |language=zh-hans}}</ref> The negative effects of sleep deprivation on alertness and cognitive performance suggest decreases in brain activity and function. These changes primarily occur in two regions: the [[thalamus]], a structure involved in alertness and attention, and the [[prefrontal cortex]], a region subserving alertness, attention, and higher-order cognitive processes.<ref name="performance" /> This was the finding of an American study in 2000. Seventeen men in their 20s were tested. Sleep deprivation was progressive, with measurements of glucose (absolute regional CMRglu), cognitive performance, alertness, mood, and subjective experiences collected after 0, 24, 48, and 72 hours of sleep deprivation. Additional measures of alertness, cognitive performance, and mood were collected at fixed intervals. [[Positron emission tomography|PET]] scans were used, and attention was paid to the circadian rhythm of cognitive performance.<ref name="performance" /> Interestingly, the effects of sleep deprivation appear to be constant across "night owls" and "early birds", or different sleep chronotypes, as revealed by [[fMRI]] and [[graph theory]].<ref>{{cite journal | vauthors = Farahani FV, Fafrowicz M, Karwowski W, Douglas PK, Domagalik A, Beldzik E, Oginska H, Marek T | title = Effects of Chronic Sleep Restriction on the Brain Functional Network, as Revealed by Graph Theory | journal = Frontiers in Neuroscience | volume = 13 | pages = 1087 | date = 11 October 2019 | pmid = 31680823 | pmc = 6807652 | doi = 10.3389/fnins.2019.01087 | publisher = Frontiers Media SA | doi-access = free }}</ref>

==== Lasting ====
[[File:Effect of REM sleep deprivation on the mitochondrial structure of neurons in rats.jpg|thumb|REM sleep deprivation causes swollen mitochondria in neurons (caused by [[cytochrome c]]); noradrenaline receptor blockers keep their inner cristae intact.]]
Studies on rodents show that the response to neuronal injury due to acute sleep deprivation is adaptative before three hours of sleep loss per night and becomes maladaptative, and [[apoptosis]] occurs after.<ref>{{cite journal | vauthors = Wu J, Dou Y, Ladiges WC | title = Adverse Neurological Effects of Short-Term Sleep Deprivation in Aging Mice Are Prevented by SS31 Peptide | journal = Clocks & Sleep | volume = 2 | issue = 3 | pages = 325–333 | date = September 2020 | pmid = 33089207 | pmc = 7573804 | doi = 10.3390/clockssleep2030024 | doi-access = free }}</ref> Studies in mice show neuronal death (in the [[hippocampus]], [[locus coeruleus]], and medial [[Prefrontal cortex|PFC]]) occurs after two days of [[Rapid eye movement sleep|REM sleep]] deprivation. However, mice do not model well the effects in humans, because they sleep a third of the duration of REM sleep of humans and [[Caspase 3|caspase-3]],  the main effector of apoptosis, kills three times the number of cells in humans than in mice.<ref>{{cite journal | vauthors = Kerr LE, McGregor AL, Amet LE, Asada T, Spratt C, Allsopp TE, Harmar AJ, Shen S, Carlson G, Logan N, Kelly JS, Sharkey J | title = Mice overexpressing human caspase 3 appear phenotypically normal but exhibit increased apoptosis and larger lesion volumes in response to transient focal cerebral ischaemia | journal = Cell Death and Differentiation | volume = 11 | issue = 10 | pages = 1102–1111 | date = October 2004 | pmid = 15153940 | doi = 10.1038/sj.cdd.4401449 | s2cid = 9525364 | doi-access = free }}</ref> Also not accounted for in nearly all of the studies is that acute REM sleep deprivation induces lasting (> 20 days) neuronal apoptosis in mice, and the apoptosis rate increases on the day following its end, so the amount of apoptosis is often undercounted in mice because experiments nearly always measure it the day the sleep deprivation ends.<ref>{{cite journal | vauthors = Soto-Rodriguez S, Lopez-Armas G, Luquin S, Ramos-Zuñiga R, Jauregui-Huerta F, Gonzalez-Perez O, Gonzalez-Castañeda RE | title = Rapid Eye Movement Sleep Deprivation Produces Long-Term Detrimental Effects in Spatial Memory and Modifies the Cellular Composition of the Subgranular Zone | journal = Frontiers in Cellular Neuroscience | volume = 10 | pages = 132 | year = 2016 | pmid = 27303266 | pmc = 4884737 | doi = 10.3389/fncel.2016.00132 | doi-access = free }}</ref>  For these reasons, both the time before cells degenerate and the extent of degeneration could be greatly underevaluated in humans.

Such [[Histology|histological]] studies cannot be performed on humans for ethical reasons, but long-term studies show that sleep quality is more associated with [[gray matter]] volume reduction<ref>{{Cite web | vauthors = Haelle T | date = 3 September 2014 |title=Poor Quality Sleep May Be Linked to Shrinking Brain |url=https://www.webmd.com/sleep-disorders/news/20140903/poor-quality-sleep-may-be-linked-to-shrinking-brain | archive-url = https://web.archive.org/web/20230309202947/https://www.webmd.com/web/20230309202947/https:/www.webmd.com/sleep-disorders/news/20140903/poor-quality-sleep-may-be-linked-to-shrinking-brain | archive-date = 9 March 2023 |access-date=9 March 2023|website=WebMD |language=en}}</ref> than age,<ref>{{cite journal | vauthors = Van Someren EJ, Oosterman JM, Van Harten B, Vogels RL, Gouw AA, Weinstein HC, Poggesi A, Scheltens P, Scherder EJ | title = Medial temporal lobe atrophy relates more strongly to sleep-wake rhythm fragmentation than to age or any other known risk | journal = Neurobiology of Learning and Memory | volume = 160 | pages = 132–138 | date = April 2019 | pmid = 29864525 | doi = 10.1016/j.nlm.2018.05.017 | series = Sleep and Hippocampal Function | s2cid = 46932040 | doi-access = free | hdl = 2066/202856 | hdl-access = free }}</ref> occurring in areas like the [[precuneus]].<ref>{{cite journal | vauthors = Grau-Rivera O, Operto G, Falcón C, Sánchez-Benavides G, Cacciaglia R, Brugulat-Serrat A, Gramunt N, Salvadó G, Suárez-Calvet M, Minguillon C, Iranzo Á, Gispert JD, Molinuevo JL | title = Association between insomnia and cognitive performance, gray matter volume, and white matter microstructure in cognitively unimpaired adults | journal = Alzheimer's Research & Therapy | volume = 12 | issue = 1 | pages = 4 | date = January 2020 | pmid = 31907066 | pmc = 6945611 | doi = 10.1186/s13195-019-0547-3 | collaboration = ALFA Study | doi-access = free }}</ref>
[[File:Molecular pathway of REMSD-induced apoptosis in neurons.jpg|left|thumb|Molecular pathway of REM sleep deprivation-induced apoptosis in neurons]]
Sleep is necessary to repair cellular damage caused by [[reactive oxygen species]] and DNA damage. During long-term sleep deprivation, cellular damage aggregates up to a tipping point that triggers cellular degeneration and apoptosis.
REM sleep deprivation causes an increase in [[Norepinephrine|noradrenaline]] (which incidentally causes the person sleep deprived to be stressed) due to the neurons in the [[locus coeruleus]] producing it not ceasing to do so, which causes an increase in the activity of the [[Sodium–potassium pump|Na⁺/K⁺-ATPase pump]], which itself activates the [[Apoptosis#Intrinsic pathway|intrinsic pathway of apoptosis]]<ref>{{cite journal | vauthors = Somarajan BI, Khanday MA, Mallick BN | title = Rapid Eye Movement Sleep Deprivation Induces Neuronal Apoptosis by Noradrenaline Acting on Alpha1 Adrenoceptor and by Triggering Mitochondrial Intrinsic Pathway | journal = Frontiers in Neurology | volume = 7 | pages = 25 | date = 2016 | pmid = 27014180 | pmc = 4779900 | doi = 10.3389/fneur.2016.00025 | doi-access = free }}</ref> and prevents autophagy, which also induces the mitochondrial pathway of apoptosis.

Sleep outside of the REM phase may allow enzymes to repair brain cell damage caused by [[radical (chemistry)|free radicals]]. High metabolic activity while awake damages the enzymes themselves, preventing efficient repair. This study observed the first evidence of brain damage in rats as a direct result of sleep deprivation.<ref name="Siegel">{{cite news | vauthors = Siegel JM |title=Why We Sleep |url=http://www.semel.ucla.edu/sleepresearch/sciam2003/sciamsleep.pdf |work=[[Scientific American]] |date=November 2003 |access-date=3 April 2008 |url-status=live |archive-url=https://web.archive.org/web/20081203071459/http://www.semel.ucla.edu/sleepresearch/sciam2003/sciamsleep.pdf |archive-date=3 December 2008  }}</ref>

===Attention and working memory===
Among the possible physical consequences of sleep deprivation, deficits in attention and [[working memory]] are perhaps the most important;<ref name="Alhola" /> such lapses in mundane routines can lead to unfortunate results, from forgetting ingredients while cooking to missing a sentence while taking notes. Performing tasks that require attention appears to be correlated with the number of hours of sleep received each night, declining as a function of hours of sleep deprivation.<ref>{{Cite book|title = An Introduction to Brain and Behavior| vauthors = Kolb B, Whishaw I |publisher = Worth Publishers|year = 2014|isbn = 978-1-4292-4228-8|location = New York, New York|pages = 468–469|edition = 4th}}</ref> Working memory is tested by methods such as choice-reaction time tasks.<ref name="Alhola" />

Attentional lapses also extend into more critical domains in which the consequences can be life or death; car crashes and industrial disasters can result from inattentiveness attributable to sleep deprivation. To empirically measure the magnitude of attention deficits, researchers typically employ the [[psychomotor vigilance task]] (PVT), which requires the subject to press a button in response to a light at random intervals. Failure to press the button in response to the stimulus (light) is recorded as an error, attributable to the microsleeps that occur as a product of sleep deprivation.<ref>{{cite journal | vauthors = Innes CR, Poudel GR, Jones RD | title = Efficient and regular patterns of nighttime sleep are related to increased vulnerability to microsleeps following a single night of sleep restriction | journal = Chronobiology International | volume = 30 | issue = 9 | pages = 1187–1196 | date = November 2013 | pmid = 23998288 | doi = 10.3109/07420528.2013.810222 | s2cid = 4682794 }}</ref>

Crucially, individuals' subjective evaluations of their fatigue often do not predict actual performance on the PVT. While totally sleep-deprived individuals are usually aware of the degree of their impairment, lapses from chronic (lesser) sleep deprivation can build up over time so that they are equal in number and severity to the lapses occurring from total (acute) sleep deprivation. Chronically sleep-deprived people, however, continue to rate themselves considerably less impaired than totally sleep-deprived participants.<ref name="SleepDepPVT">{{cite journal | vauthors = Van Dongen HP, Maislin G, Mullington JM, Dinges DF | title = The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation | journal = Sleep | volume = 26 | issue = 2 | pages = 117–126 | date = March 2003 | pmid = 12683469 | doi = 10.1093/sleep/26.2.117 | url = http://www.aasmnet.org/Resources/FactSheets/DrowsyDriving.pdf | url-status = live | doi-access = free | archive-url = https://web.archive.org/web/20110718152642/http://www.aasmnet.org/Resources/FactSheets/DrowsyDriving.pdf | archive-date = 18 July 2011 }}</ref> Since people usually evaluate their capability on tasks like driving subjectively, their evaluations may lead them to the false conclusion that they can perform tasks that require constant attention when their abilities are in fact impaired.{{cn|date=April 2023}}

=== Mood ===
Sleep deprivation can have a negative impact on mood.<ref>{{cite journal | vauthors = Kramer M, Roehrs T, Roth T | title = Mood change and the physiology of sleep | journal = Comprehensive Psychiatry | volume = 17 | issue = 1 | pages = 161–165 | date = January 1976 | pmid = 174865 | doi = 10.1016/0010-440x(76)90065-1 }}</ref> Staying up all night or taking an unexpected night shift can make one feel irritable. Once one catches up on sleep, one's mood will often return to baseline or normal. Even partial sleep deprivation can have a significant impact on mood. In one study, subjects reported increased sleepiness, fatigue, confusion, tension, and total mood disturbance, which all recovered to their baseline after one to two full nights of sleep.<ref name=":0">{{Cite web|title=Sleep and Mood {{!}} Need Sleep|url=http://healthysleep.med.harvard.edu/need-sleep/whats-in-it-for-you/mood#1.|access-date=21 January 2021|website=healthysleep.med.harvard.edu|archive-date=21 March 2021|archive-url=https://web.archive.org/web/20210321052445/http://healthysleep.med.harvard.edu/need-sleep/whats-in-it-for-you/mood#1.|url-status=dead}}</ref><ref>{{cite journal | vauthors = Dinges DF, Pack F, Williams K, Gillen KA, Powell JW, Ott GE, Aptowicz C, Pack AI | title = Cumulative sleepiness, mood disturbance, and psychomotor vigilance performance decrements during a week of sleep restricted to 4-5 hours per night | journal = Sleep | volume = 20 | issue = 4 | pages = 267–277 | date = April 1997 | pmid = 9231952 }}</ref>

[[Depression (mood)|Depression]] and sleep are in a bidirectional relationship. Poor sleep can lead to the development of depression, and depression can cause [[insomnia]], [[hypersomnia]], or [[obstructive sleep apnea]].<ref>{{Cite web|title=Depression and Sleep|url=https://www.sleepfoundation.org/mental-health/depression-and-sleep|access-date=21 January 2021|website=Sleep Foundation |date=18 September 2020 |language=en}}</ref><ref>{{cite journal | vauthors = Franzen PL, Buysse DJ | title = Sleep disturbances and depression: risk relationships for subsequent depression and therapeutic implications | journal = Dialogues in Clinical Neuroscience | volume = 10 | issue = 4 | pages = 473–481 | date = 2008 | pmid = 19170404 | pmc = 3108260 | doi = 10.31887/DCNS.2008.10.4/plfranzen }}</ref> About 75% of adult patients with depression can present with insomnia.<ref>{{cite journal | vauthors = Nutt D, Wilson S, Paterson L | title = Sleep disorders as core symptoms of depression | journal = Dialogues in Clinical Neuroscience | volume = 10 | issue = 3 | pages = 329–336 | date = 2008 | pmid = 18979946 | pmc = 3181883 | doi = 10.31887/DCNS.2008.10.3/dnutt }}</ref> Sleep deprivation, whether total or not, can induce significant anxiety, and longer sleep deprivations tend to result in an increased level of anxiety.<ref>{{cite journal | vauthors = Pires GN, Bezerra AG, Tufik S, Andersen ML | title = Effects of acute sleep deprivation on state anxiety levels: a systematic review and meta-analysis | journal = Sleep Medicine | volume = 24 | pages = 109–118 | date = August 2016 | pmid = 27810176 | doi = 10.1016/j.sleep.2016.07.019 }}</ref>

Sleep deprivation has also shown some positive effects on mood and can be used to treat depression.<ref name="Sleep and depression review" /> Chronotype can affect how sleep deprivation influences mood. Those with morningness (advanced sleep period or "lark") preference become more depressed after sleep deprivation, while those with eveningness (delayed sleep period or "owl") preference show an improvement in mood.<ref>{{cite journal | vauthors = Selvi Y, Gulec M, Agargun MY, Besiroglu L | title = Mood changes after sleep deprivation in morningness-eveningness chronotypes in healthy individuals | journal = Journal of Sleep Research | volume = 16 | issue = 3 | pages = 241–244 | date = September 2007 | pmid = 17716271 | doi = 10.1111/j.1365-2869.2007.00596.x | url = http://dl.dropboxusercontent.com/u/85192141/2006-selvi.pdf | url-status = live | s2cid = 42338269 | doi-access = free | archive-url = https://web.archive.org/web/20141215025258/https://dl.dropboxusercontent.com/u/85192141/2006-selvi.pdf | archive-date = 15 December 2014 }}</ref>

Mood and mental states can affect sleep as well. Increased agitation and arousal from anxiety or stress can keep one more aroused, awake, and alert.<ref name=":0" />

===Driving ability===
{{main|Sleep-deprived driving}}
The dangers of sleep deprivation are apparent on the road; the [[American Academy of Sleep Medicine]] (AASM) reports that one in every five serious motor vehicle injuries is related to driver fatigue, with 80,000 drivers falling asleep behind the wheel every day and 250,000 accidents every year related to sleep,<ref name="DrowsyDriving">{{cite web |title=Drowsy Driving Fact Sheet |url=http://www.aasmnet.org/Resources/FactSheets/DrowsyDriving.pdf |work=American Academy of Sleep Medicine |date=2 December 2009 |url-status=live |archive-url=https://web.archive.org/web/20110718152642/http://www.aasmnet.org/Resources/FactSheets/DrowsyDriving.pdf |archive-date=18 July 2011  }}</ref> though the National Highway Traffic Safety Administration suggests the figure for [[traffic accidents]] may be closer to 100,000.<ref name="SleepDepReport">{{cite journal| vauthors = Carpenter S |author-link=Siri Carpenter|year=2001|title=Sleep deprivation may be undermining teen health|url=http://www.apa.org/monitor/oct01/sleepteen.html|url-status=live|journal=Monitor on Psychology|volume=32|issue=9|page=42|archive-url=https://web.archive.org/web/20061006064800/http://www.apa.org/monitor/oct01/sleepteen.html|archive-date=6 October 2006}}</ref> The AASM recommends pulling off the road and taking a 15- or 20-minute nap to alleviate drowsiness.<ref name="DrowsyDriving" />

According to a 2000 study published in the ''[[British Medical Journal]]'', researchers in Australia and New Zealand reported that sleep deprivation can have some of the same hazardous effects as being drunk.<ref name="Drunkhazard">{{cite journal | vauthors = Williamson AM, Feyer AM | title = Moderate sleep deprivation produces impairments in cognitive and motor performance equivalent to legally prescribed levels of alcohol intoxication | journal = Occupational and Environmental Medicine | volume = 57 | issue = 10 | pages = 649–655 | date = October 2000 | pmid = 10984335 | pmc = 1739867 | doi = 10.1136/oem.57.10.649 }}</ref> People who drove after being awake for 17–19 hours performed worse than those with a blood alcohol level of 0.05 percent, which is the legal limit for drunk driving in most western European countries and Australia. Another study suggested that performance begins to degrade after 16 hours awake, and 21 hours awake was equivalent to a blood alcohol content of 0.08 percent, which is the [[blood alcohol limit]] for drunk driving in Canada, the U.S., and the U.K.<ref name="FatigueandAlcohol">{{cite journal | vauthors = Dawson D, Reid K | title = Fatigue, alcohol and performance impairment | journal = Nature | volume = 388 | issue = 6639 | pages = 235 | date = July 1997 | pmid = 9230429 | doi = 10.1038/40775 | s2cid = 4424846 | bibcode = 1997Natur.388..235D | doi-access = free }}</ref>

The fatigue of drivers of goods trucks and passenger vehicles has come to the attention of authorities in many countries, where specific laws have been introduced with the aim of reducing the risk of traffic accidents due to driver fatigue. Rules concerning minimum break lengths, maximum shift lengths, and minimum time between shifts are common in the driving regulations used in different countries and regions, such as the [[drivers' working hours]] regulations in the European Union and [[hours of service]] regulations in the United States.

The [[Exxon Valdez Oil Spill]] was the second largest oil spill in United States waters, after the 2010 Deepwater Horizon oil spill. This accident occurred when an Exxon oil tanker struck a reef at [[Prince William Sound]] in Alaska. Approximately 10.8 million gallons of oil spilled into the sea. The accident caused great environmental damage, including the deaths of hundreds of thousands of birds and sea creatures. Fatigue and sleep deprivation were the major contributors to the accident. The captain of the ship was asleep after a night of heavy drinking; he was severely fatigued and had been awake for 18 hours. The entire crew was suffering from fatigue and inadequate sleep.<ref>{{ProQuest|2092623770}}</ref>

===Fatigue===
Sleep deprivation and disruption is associated with subsequent [[fatigue]].
<ref>{{cite book | chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK384963 | title=Commercial Motor Vehicle Driver Fatigue, Long-Term Health, and Highway Safety: Research Needs | chapter=Consequences of Fatigue from Insufficient Sleep | date=12 August 2016 | publisher=National Academies Press (US) }}</ref><ref>{{cite journal | doi=10.3389/fnins.2022.930280 | doi-access=free | title=Predicting and mitigating fatigue effects due to sleep deprivation: A review | date=2022 | last1=Kayser | first1=Kylie C. | last2=Puig | first2=Vannia A. | last3=Estepp | first3=Justin R. | journal=Frontiers in Neuroscience | volume=16 | pmid=35992930 | pmc=9389006 }}</ref>

===Sleep transition===
Sleep propensity (SP) can be defined as the readiness to transition from wakefulness to sleep or the ability to stay asleep if already sleeping.<ref>{{cite book | vauthors = Schulz H, Bes E, Jobert M | chapter = Modelling sleep propensity and sleep disturbances. | title = Sleep—Wake Disorders | date = 1998 | pages = 11–26 | location = Boston, MA | publisher = Springer US | doi = 10.1007/978-1-4899-0245-0_2 | isbn = 978-1-4899-0247-4 }}</ref> Sleep deprivation increases this propensity, which can be measured by polysomnography (PSG) as a reduction in sleep latency (the time needed to fall asleep).<ref name="Durmer2005">{{cite journal | vauthors = Durmer JS, Dinges DF | title = Neurocognitive consequences of sleep deprivation | journal = Seminars in Neurology | volume = 25 | issue = 1 | pages = 117–129 | date = March 2005 | pmid = 15798944 | pmc = 3564638 | doi = 10.1055/s-2005-867080 }}</ref> An indicator of sleep propensity can also be seen in the shortening of the transition from light stages of non-REM sleep to deeper slow-wave oscillations.<ref name="Durmer2005" />

On average, the latency in healthy adults decreases by a few minutes after a night without sleep, and the latency from sleep onset to slow-wave sleep is halved.<ref name="Durmer2005" /> Sleep latency is generally measured with the multiple sleep latency test (MSLT). In contrast, the maintenance of wakefulness test (MWT) also uses sleep latency, but this time as a measure of the capacity of the participants to stay awake (when asked to) instead of falling asleep.<ref name="Durmer2005" />

===Sleep-wake cycle===
People aged 18 to 64 need seven to nine hours of sleep per night.<ref>{{Cite web |date=2022-03-25 |title=Here's What Happens When You Don't Get Enough Sleep (And How Much You Really Need a Night) |url=https://health.clevelandclinic.org/happens-body-dont-get-enough-sleep/ |access-date=2022-04-17 |website=Cleveland Clinic |language=en-US}}</ref> Research studying sleep deprivation shows its impact on mood, cognitive, and motor functioning due to dysregulation of the sleep-wake cycle and augmented sleep propensity.<ref name="Durmer2005" /> Multiple studies that identified the role of the [[hypothalamus]] and multiple neural systems controlling circadian rhythms and homeostasis have been helpful in understanding sleep deprivation better.<ref name="Durmer2005" /><ref>{{cite journal | vauthors = Saper CB, Chou TC, Scammell TE | title = The sleep switch: hypothalamic control of sleep and wakefulness | journal = Trends in Neurosciences | volume = 24 | issue = 12 | pages = 726–731 | date = December 2001 | pmid = 11718878 | doi = 10.1016/S0166-2236(00)02002-6 | s2cid = 206027570 }}</ref> To describe the temporal course of the sleep-wake cycle, the two-process model of sleep regulation can be mentioned.<ref name="Durmer2005" />

This model proposes a homeostatic process (Process S) and a circadian process (Process C) that interact to define the time and intensity of sleep.<ref name="Borbély2016">{{cite journal | vauthors = Borbély AA, Daan S, Wirz-Justice A, Deboer T | title = The two-process model of sleep regulation: a reappraisal | journal = Journal of Sleep Research | volume = 25 | issue = 2 | pages = 131–143 | date = April 2016 | pmid = 26762182 | doi = 10.1111/jsr.12371 | doi-access = free }}</ref> Process S represents the drive for sleep, increasing during wakefulness and decreasing during sleep until a defined threshold level, while Process C is the oscillator responsible for these levels. When being sleep deprived, homeostatic pressure accumulates to the point that waking functions will be degraded even at the highest circadian drive for wakefulness.<ref name="Durmer2005" /><ref name="Borbély2016" />

===Microsleeps===
[[Microsleep]]s are periods of brief sleep that most frequently occur when a person has a significant level of sleep deprivation. Microsleeps usually last for a few seconds, usually no longer than 15 seconds,<ref>{{cite journal | vauthors = Skorucak J, Hertig-Godeschalk A, Schreier DR, Malafeev A, Mathis J, Achermann P | title = Automatic detection of microsleep episodes with feature-based machine learning | journal = Sleep | volume = 43 | issue = 1 | pages = zsz225 | date = January 2020 | pmid = 31559424 | doi = 10.1093/sleep/zsz225 | doi-access = free }}</ref> and happen most frequently when a person is trying to stay awake when they are feeling sleepy.<ref>{{Cite web|url = http://healthysleep.med.harvard.edu/need-sleep/glossary/k-m|title = Glossary K-M|date = 2012|website = Get Sleep|publisher = Harvard Medical School|url-status = live|archive-url = https://web.archive.org/web/20150402122751/http://healthysleep.med.harvard.edu/need-sleep/glossary/k-m|archive-date = 2 April 2015|df = dmy-all}}</ref> The person usually falls into microsleep while doing a monotonous task like driving, reading a book, or staring at a [[computer]].<ref>{{Cite web|title = Microsleep {{!}} Microsleeps|url = http://www.sleepdex.org/microsleep.htm|website = www.sleepdex.org|access-date = 14 February 2016|url-status = live|archive-url = https://web.archive.org/web/20160303102646/http://www.sleepdex.org/microsleep.htm|archive-date = 3 March 2016|df = dmy-all}}</ref> Microsleeps are similar to [[syncope (medicine)|blackouts]], and a person experiencing them is not consciously aware that they are occurring.

An even lighter type of sleep has been seen in rats that have been kept awake for long periods of time. In a process known as [[local sleep]], specific localized brain regions went into periods of short (~80 ms) but frequent (~40/min) NREM-like states. Despite the on-and-off periods where neurons shut off, the rats appeared to be awake, although they performed poorly at tests.<ref>{{cite journal | vauthors = Vyazovskiy VV, Olcese U, Hanlon EC, Nir Y, Cirelli C, Tononi G | title = Local sleep in awake rats | journal = Nature | volume = 472 | issue = 7344 | pages = 443–447 | date = April 2011 | pmid = 21525926 | pmc = 3085007 | doi = 10.1038/nature10009 | bibcode = 2011Natur.472..443V }}</ref>

=== Cardiovascular morbidity ===
Decreased sleep duration is associated with many adverse cardiovascular consequences.<ref>{{Cite web|date=13 February 2019|title=CDC - Sleep and Chronic Disease - Sleep and Sleep Disorders|url=https://www.cdc.gov/sleep/about_sleep/chronic_disease.html|access-date=21 January 2021|website=www.cdc.gov|language=en-us}}</ref><ref>{{cite journal | vauthors = Knutson KL, Van Cauter E, Rathouz PJ, Yan LL, Hulley SB, Liu K, Lauderdale DS | title = Association between sleep and blood pressure in midlife: the CARDIA sleep study | journal = Archives of Internal Medicine | volume = 169 | issue = 11 | pages = 1055–1061 | date = June 2009 | pmid = 19506175 | pmc = 2944774 | doi = 10.1001/archinternmed.2009.119 }}</ref><ref>{{cite journal | vauthors = King CR, Knutson KL, Rathouz PJ, Sidney S, Liu K, Lauderdale DS | title = Short sleep duration and incident coronary artery calcification | journal = JAMA | volume = 300 | issue = 24 | pages = 2859–2866 | date = December 2008 | pmid = 19109114 | pmc = 2661105 | doi = 10.1001/jama.2008.867 }}</ref><ref>{{cite journal | vauthors = Sabanayagam C, Shankar A | title = Sleep duration and cardiovascular disease: results from the National Health Interview Survey | journal = Sleep | volume = 33 | issue = 8 | pages = 1037–1042 | date = August 2010 | pmid = 20815184 | pmc = 2910533 | doi = 10.1093/sleep/33.8.1037 }}</ref> The [[American Heart Association]] has stated that sleep restriction is a risk factor for adverse cardiometabolic profiles and outcomes. The organization recommends healthy sleep habits for ideal cardiac health, along with other well-known factors like blood pressure, cholesterol, diet, glucose, weight, smoking, and physical activity.<ref>{{cite journal | vauthors = St-Onge MP, Grandner MA, Brown D, Conroy MB, Jean-Louis G, Coons M, Bhatt DL | title = Sleep Duration and Quality: Impact on Lifestyle Behaviors and Cardiometabolic Health: A Scientific Statement From the American Heart Association | journal = Circulation | volume = 134 | issue = 18 | pages = e367–e386 | date = November 2016 | pmid = 27647451 | pmc = 5567876 | doi = 10.1161/CIR.0000000000000444 }}</ref> The [[Centers for Disease Control and Prevention]] has noted that adults who sleep less than seven hours per day are more likely to have chronic health conditions, including heart attack, coronary heart disease, and stroke, compared to those with an adequate amount of sleep.<ref>{{Cite web|date=5 March 2019|title=CDC - Data and Statistics - Sleep and Sleep Disorders|url=https://www.cdc.gov/sleep/data_statistics.html|access-date=21 January 2021|website=www.cdc.gov|language=en-us}}</ref>

In a study that followed over 160,000 healthy, non-obese adults, the subjects who self-reported sleep duration less than six hours a day were at increased risk for developing multiple cardiometabolic risk factors. They presented with increased central obesity, elevated fasting glucose, hypertension, low high-density lipoprotein, hypertriglyceridemia, and metabolic syndrome. The presence or lack of insomnia symptoms did not modify the effects of sleep duration in this study.<ref>{{cite journal | vauthors = Deng HB, Tam T, Zee BC, Chung RY, Su X, Jin L, Chan TC, Chang LY, Yeoh EK, Lao XQ | title = Short Sleep Duration Increases Metabolic Impact in Healthy Adults: A Population-Based Cohort Study | journal = Sleep | volume = 40 | issue = 10 | date = October 2017 | pmid = 28977563 | doi = 10.1093/sleep/zsx130 | doi-access = free }}</ref>

The United Kingdom Biobank studied nearly 500,000 adults who had no cardiovascular disease, and the subjects who slept less than six hours a day were associated with a 20 percent increase in the risk of developing myocardial infarction (MI) over a seven-year follow-up period. Interestingly, a long sleep duration of more than nine hours a night was also a risk factor.<ref>{{cite journal | vauthors = Daghlas I, Dashti HS, Lane J, Aragam KG, Rutter MK, Saxena R, Vetter C | title = Sleep Duration and Myocardial Infarction | journal = Journal of the American College of Cardiology | volume = 74 | issue = 10 | pages = 1304–1314 | date = September 2019 | pmid = 31488267 | pmc = 6785011 | doi = 10.1016/j.jacc.2019.07.022 }}</ref>

=== Immunosuppression ===
Among the myriad of health consequences that sleep deprivation can cause, disruption of the immune system is one of them. While it is not clearly understood, researchers believe that sleep is essential to providing sufficient energy for the immune system to work and allowing inflammation to take place during sleep. Also, just as sleep can reinforce memory in a person's brain, it can help consolidate the memory of the immune system, or [[Adaptive immune system|adaptive immunity]].<ref name=":1">{{Cite web|title=Sleep & Immunity: Can a Lack of Sleep Make You Sick?|url=https://www.sleepfoundation.org/physical-health/how-sleep-affects-immunity|access-date=21 January 2021|website=Sleep Foundation|date=26 October 2018 |language=en}}</ref><ref>{{cite journal | vauthors = Irwin MR | title = Sleep and inflammation: partners in sickness and in health | journal = Nature Reviews. Immunology | volume = 19 | issue = 11 | pages = 702–715 | date = November 2019 | pmid = 31289370 | doi = 10.1038/s41577-019-0190-z | s2cid = 195847558 }}</ref>

Sleep quality is directly related to immunity levels. The team, led by Professor Cohen of Carnegie Mellon University in the United States, found that even a slight disturbance of sleep may affect the body's response to the cold virus. Those with better sleep quality had significantly higher blood T and B lymphocytes than those with poor sleep quality.These two lymphocytes are the main body of immune function in the human body.<ref>{{Cite web |title=睡眠好坏直接影响免疫力--健康·生活--人民网 |url=http://health.people.com.cn/n1/2020/0331/c14739-31655366.html |access-date=2023-12-05 |website=health.people.com.cn}}</ref>

An adequate amount of sleep improves the effects of vaccines that utilize adaptive immunity. When vaccines expose the body to a weakened or deactivated antigen, the body initiates an immune response. The immune system learns to recognize that antigen and attacks it when exposed again in the future. Studies have found that people who don't sleep the night after getting a vaccine are less likely to develop a proper immune response to the vaccine and sometimes even require a second dose. {{Citation needed|date=June 2023}} People who are sleep deprived in general also do not provide their bodies with sufficient time for an adequate immunological memory to form and, thus, can fail to benefit from vaccination.<ref name=":1" />

People who sleep less than six hours a night are more susceptible to infection and are more likely to catch a cold or flu. A lack of sleep can also prolong the recovery time of patients in the intensive care unit (ICU).<ref name=":1" /><ref>{{cite journal | vauthors = Prather AA, Janicki-Deverts D, Hall MH, Cohen S | title = Behaviorally Assessed Sleep and Susceptibility to the Common Cold | journal = Sleep | volume = 38 | issue = 9 | pages = 1353–1359 | date = September 2015 | pmid = 26118561 | pmc = 4531403 | doi = 10.5665/sleep.4968 }}</ref><ref>{{cite journal | vauthors = Pisani MA, Friese RS, Gehlbach BK, Schwab RJ, Weinhouse GL, Jones SF | title = Sleep in the intensive care unit | journal = American Journal of Respiratory and Critical Care Medicine | volume = 191 | issue = 7 | pages = 731–738 | date = April 2015 | pmid = 25594808 | pmc = 5447310 | doi = 10.1164/rccm.201411-2099CI }}</ref>

===Weight gain ===
{{main|Sleep and weight}}
A lack of sleep can cause an imbalance in several hormones that are critical for weight gain. Sleep deprivation increases the level of ghrelin (hunger hormone) and decreases the level of leptin (fullness hormone), resulting in an increased feeling of hunger and a desire for high-calorie foods.<ref name="VanCauter">{{cite journal | vauthors = Van Cauter E, Spiegel K | title = Sleep as a mediator of the relationship between socioeconomic status and health: a hypothesis | journal = Annals of the New York Academy of Sciences | volume = 896 | issue = 1 | pages = 254–261 | year = 1999 | pmid = 10681902 | doi = 10.1111/j.1749-6632.1999.tb08120.x | bibcode = 1999NYASA.896..254V | s2cid = 36513336 }}</ref><ref name="RatExperiments"/> Sleep loss is also associated with decreased growth hormone and elevated cortisol levels, which are connected to obesity. People who do not get sufficient sleep can also feel sleepy and fatigued during the day and get less exercise. Obesity can cause poor sleep quality as well. Individuals who are overweight or obese can experience obstructive sleep apnea, gastroesophageal reflux disease (GERD), depression, asthma, and osteoarthritis, all of which can disrupt a good night's sleep.<ref>{{Cite web|title=The Link Between Obesity and Sleep Deprivation|url=https://www.sleepfoundation.org/physical-health/obesity-and-sleep|access-date=21 January 2021|website=Sleep Foundation|date=4 December 2020 |language=en}}</ref>

In rats, prolonged, complete sleep deprivation increased both food intake and energy expenditure, with a net effect of weight loss and ultimately death.<ref>{{cite journal | vauthors = Everson CA, Bergmann BM, Rechtschaffen A | title = Sleep deprivation in the rat: III. Total sleep deprivation | journal = Sleep | volume = 12 | issue = 1 | pages = 13–21 | date = February 1989 | pmid = 2928622 | doi = 10.1093/sleep/12.1.13 | doi-access = free }}</ref> This study hypothesizes that the moderate chronic [[sleep debt]] associated with habitual short sleep is associated with increased appetite and energy expenditure, with the equation tipped towards food intake rather than expenditure in societies where high-calorie food is freely available.<ref name="RatExperiments">{{cite journal | vauthors = Taheri S, Lin L, Austin D, Young T, Mignot E | title = Short sleep duration is associated with reduced leptin, elevated ghrelin, and increased body mass index | journal = PLOS Medicine | volume = 1 | issue = 3 | pages = e62 | date = December 2004 | pmid = 15602591 | pmc = 535701 | doi = 10.1371/journal.pmed.0010062 | doi-access = free }}</ref>

===Type 2 diabetes===
It has been suggested that people experiencing short-term sleep restrictions process glucose more slowly than individuals receiving a full 8 hours of sleep, increasing the likelihood of developing type 2 [[diabetes]].<ref>{{Cite web|date=2007|title=Sleep and Disease Risk|url=http://healthysleep.med.harvard.edu/healthy/matters/consequences/sleep-and-disease-risk|url-status=live|archive-url=https://web.archive.org/web/20160325003506/http://healthysleep.med.harvard.edu/healthy/matters/consequences/sleep-and-disease-risk|archive-date=25 March 2016|website=Healthy Sleep|publisher=Harvard Medical School}}</ref> Poor sleep quality is linked to high blood sugar levels in diabetic and prediabetic patients, but the causal relationship is not clearly understood. Researchers suspect that sleep deprivation affects insulin, cortisol, and oxidative stress, which subsequently influence blood sugar levels. Sleep deprivation can increase the level of [[ghrelin]] and decrease the level of [[leptin]]. People who get insufficient amounts of sleep are more likely to crave food in order to compensate for the lack of energy. This habit can raise blood sugar and put them at risk of [[obesity]] and diabetes.<ref>{{Cite web|title=Diabetes and Sleep: Sleep Disturbances & Coping|url=https://www.sleepfoundation.org/physical-health/lack-of-sleep-and-diabetes|access-date=21 January 2021|website=Sleep Foundation|date=20 November 2020|language=en}}</ref>

In 2005, a study of over 1400 participants showed that participants who habitually slept fewer hours were more likely to have associations with [[type 2 diabetes]].<ref name="DGottlieb">{{cite journal | vauthors = Gottlieb DJ, Punjabi NM, Newman AB, Resnick HE, Redline S, Baldwin CM, Nieto FJ | title = Association of sleep time with diabetes mellitus and impaired glucose tolerance | journal = Archives of Internal Medicine | volume = 165 | issue = 8 | pages = 863–867 | date = April 2005 | pmid = 15851636 | doi = 10.1001/archinte.165.8.863 | doi-access = free }}</ref> However, because this study was merely correlational, the direction of cause and effect between little sleep and diabetes is uncertain. The authors point to an earlier study that showed that experimental rather than habitual restriction of sleep resulted in [[impaired glucose tolerance]] (IGT).<ref>{{cite journal | vauthors = Spiegel K, Leproult R, Van Cauter E | title = Impact of sleep debt on metabolic and endocrine function | journal = Lancet | volume = 354 | issue = 9188 | pages = 1435–1439 | date = October 1999 | pmid = 10543671 | doi = 10.1016/S0140-6736(99)01376-8 | s2cid = 3854642 }}</ref>

===Other effects===

The National Sleep Foundation identifies several warning signs that a driver is dangerously fatigued. These include rolling down the window, turning up the radio, having trouble keeping eyes open, head-nodding, drifting out of their lane, and daydreaming. At particular risk are lone drivers between midnight and 6:00 a.m.<ref name="SleepFoundationDrowsyDriving">{{cite web|date=2 December 2009|title=Drowsy Driving:Key Messages and Talking Points|url=http://www.sleepfoundation.org/sites/default/files/Drowsy%20Driving-Key%20Messages%20and%20Talking%20Points.pdf|url-status=live|archive-url=https://web.archive.org/web/20131126062848/http://www.sleepfoundation.org/sites/default/files/Drowsy%20Driving-Key%20Messages%20and%20Talking%20Points.pdf|archive-date=26 November 2013|work=National Sleep Foundation}}</ref>

Sleep deprivation can negatively impact overall performance and has led to major fatal accidents. Due largely to the February 2009 crash of [[Colgan Air Flight 3407]], which killed 50 people and was partially attributed to pilot fatigue, the FAA reviewed its procedures to ensure that pilots are sufficiently rested. Air traffic controllers were under scrutiny when, in 2010, there were 10 incidents of controllers falling asleep while on shift.  The common practice of turn-around shifts caused sleep deprivation and was a contributing factor to all air traffic control incidents.  The FAA reviewed its practices for shift changes, and the findings showed that controllers were not well rested.<ref name="PlaneCrash">{{cite web|date=10 September 2010|title=Fact Sheet – Pilot Fatigue|url=http://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=11857|url-status=live|archive-url=https://web.archive.org/web/20161005194346/http://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=11857|archive-date=5 October 2016|work=Federal Aviation Administration}}</ref> A 2004 study also found medical residents with less than four hours of sleep a night made more than twice as many errors as the 11% of surveyed residents who slept for more than seven hours a night.<ref name="MedicalErrors">{{cite journal | vauthors = Baldwin DC, Daugherty SR | title = Sleep deprivation and fatigue in residency training: results of a national survey of first- and second-year residents | journal = Sleep | volume = 27 | issue = 2 | pages = 217–223 | date = March 2004 | pmid = 15124713 | doi = 10.1093/sleep/27.2.217 | doi-access = free }}</ref>

Twenty-four hours of continuous sleep deprivation results in the choice of less difficult math tasks without a decrease in subjective reports of effort applied to the task.{{Citation needed|date=June 2023}} Naturally occurring sleep loss affects the choice of everyday tasks, such that low-effort tasks are mostly commonly selected.{{Citation needed|date=June 2023}} [[Adolescents]] who experience less sleep show a decreased willingness to engage in sports activities that require effort through fine motor coordination and attention to detail.<ref>{{cite journal | vauthors = Engle-Friedman M, Riela S, Golan R, Ventuneac AM, Davis CM, Jefferson AD, Major D | title = The effect of sleep loss on next day effort | journal = Journal of Sleep Research | volume = 12 | issue = 2 | pages = 113–124 | date = June 2003 | pmid = 12753348 | doi = 10.1046/j.1365-2869.2003.00351.x | s2cid = 13519528 }}</ref><ref>{{cite journal | vauthors = Engle-Friedman M, Palencar V, Riela S | title = Sleep and effort in adolescent athletes | journal = Journal of Child Health Care | volume = 14 | issue = 2 | pages = 131–141 | date = June 2010 | pmid = 20435615 | doi = 10.1177/1367493510362129 | s2cid = 7680316 }}</ref>

Great sleep deprivation mimics psychosis: distorted perceptions can lead to inappropriate emotional and behavioral responses.<ref name="Coren">{{cite journal| vauthors = Coren S |date=1 March 1998|title=Sleep Deprivation, Psychosis and Mental Efficiency|url=http://www.psychiatrictimes.com/display/article/10168/54471|url-status=live|journal=Psychiatric Times|volume=15|issue=3|archive-url=https://web.archive.org/web/20090904142025/http://www.psychiatrictimes.com/display/article/10168/54471|archive-date=4 September 2009|access-date=25 November 2009}}</ref>

Astronauts have reported [[Performance Errors due to Fatigue and Sleep Loss During Spaceflight|performance errors and decreased cognitive ability]] during periods of extended working hours and wakefulness, as well as sleep loss caused by circadian rhythm disruption and environmental factors.<ref>{{cite web| vauthors = Whitmire AM, Leveton LB, Barger L, Brainard G, Dinges DF, Klerman E, Shea C |title=Risk of Performance Errors due to Sleep Loss, Circadian Desynchronization, Fatigue, and Work Overload|url=http://humanresearchroadmap.nasa.gov/evidence/reports/Sleep.pdf|url-status=live|archive-url=https://web.archive.org/web/20120215234226/http://humanresearchroadmap.nasa.gov/evidence/reports/Sleep.pdf|archive-date=15 February 2012|access-date=25 June 2012|work=Human Health and Performance Risks of Space Exploration Missions: Evidence reviewed by the NASA Human Research Program}}</ref>

One study has found that a single night of sleep deprivation may cause tachycardia, a condition in which the heartrate exceeds 100 beats per minute (in the following day).<ref>{{Cite web |title=Tachycardia - Symptoms and causes |url=https://www.mayoclinic.org/diseases-conditions/tachycardia/symptoms-causes/syc-20355127 |access-date=2022-06-27 |website=Mayo Clinic |language=en}}</ref><ref name="sleeptachy">{{cite journal | vauthors = Rangaraj VR, Knutson KL | title = Association between sleep deficiency and cardiometabolic disease: implications for health disparities | journal = Sleep Medicine | volume = 18 | pages = 19–35 | date = February 2016 | pmid = 26431758 | pmc = 4758899 | doi = 10.1016/j.sleep.2015.02.535 }}</ref>

Generally, sleep deprivation may facilitate or intensify:<ref name="SleepDep">{{cite web|title=Sleep deprivation|url=http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Sleep_deprivation?OpenDocument|url-status=dead|archive-url=https://web.archive.org/web/20090820003333/http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Sleep_deprivation?OpenDocument|archive-date=20 August 2009|work=betterhealth.vic.gov.au}}</ref>
* aching muscles<ref>{{cite book| vauthors = Morin CM |url=https://archive.org/details/springer_10.1007-b105845|title=Insomnia|publisher=Kluwer Academic/Plenum Publ.|year=2003|isbn=978-0-306-47750-8|location=New York|page=[https://archive.org/details/springer_10.1007-b105845/page/n39 28] death}}</ref>
*[[confusion]], [[memory]] lapses or loss<ref name="BrainBasics">{{cite web | url = http://www.ninds.nih.gov/disorders/brain_basics/understanding_sleep.htm | work = National Institute of Neurological Disorders and Stroke | title = Brain Basics: Understanding Sleep | archive-url = https://web.archive.org/web/20071011011207/http://www.ninds.nih.gov/disorders/brain_basics/understanding_sleep.htm| archive-date=11 October 2007}}</ref>
* [[depression (mood)|depression]]<ref name="BrainBasics" />
* development of [[false memory]]
* [[hypnagogic]] and [[hypnopompic]] [[hallucination]]s during falling asleep and waking, which are entirely normal<ref name="Ohayon_et_al_1996">{{cite journal | vauthors = Ohayon MM, Priest RG, Caulet M, Guilleminault C | title = Hypnagogic and hypnopompic hallucinations: pathological phenomena? | journal = The British Journal of Psychiatry | volume = 169 | issue = 4 | pages = 459–467 | date = October 1996 | pmid = 8894197 | doi = 10.1192/bjp.169.4.459 | s2cid = 3086394 }}</ref>
* hand [[tremor]]<ref>{{cite book| vauthors = Smith AP |title=Handbook of Human Performance|publisher=Acad. Press|year=1992|isbn=978-0-12-650352-4|location=London|page=240}}</ref>
* [[headaches]]
* [[malaise]]
* [[stye]]
* [[periorbital puffiness]], commonly known as "bags under eyes" or [[eye bags]]
* increased [[blood pressure]]<ref name="health.harvard.edu">{{cite web|date=31 May 2012|title=Harvard Heart Letter examines the costs of not getting enough sleep – Harvard Health Publications|url=http://www.health.harvard.edu/press_releases/sleep_deprivation_problem.htm|url-status=live|archive-url=https://web.archive.org/web/20110509104601/http://www.health.harvard.edu/press_releases/sleep_deprivation_problem.htm|archive-date=9 May 2011|access-date=13 August 2012|publisher=Health.harvard.edu}}</ref>
* increased [[stress hormone]] levels<ref name="health.harvard.edu" />
* increased risk of type 2 [[diabetes]]<ref name="health.harvard.edu" />
* lowering of [[immunity (medical)|immunity]], increased susceptibility to illness<ref>{{cite web| vauthors = Olson E |date=9 June 2015|title=Lack of sleep: Can it make you sick?|url=https://www.mayoclinic.org/diseases-conditions/insomnia/expert-answers/lack-of-sleep/faq-20057757|access-date=26 August 2018|publisher=[[Mayo Clinic]]}}</ref>
* increased risk of [[fibromyalgia]]<ref>{{cite web|title=The Role of Magnesium in Fibromyalgia|url=http://web.mit.edu/london/www/magnesium.html|url-status=live|archive-url=https://web.archive.org/web/20120729085013/http://web.mit.edu/london/www/magnesium.html|archive-date=29 July 2012|access-date=13 August 2012|publisher=Web.mit.edu}}</ref>
* [[irritability]]<ref name="SleepDep" />
* [[nystagmus]] (rapid involuntary rhythmic eye movement)<ref>{{cite journal | vauthors = Citek K, Ball B, Rutledge DA | title = Nystagmus testing in intoxicated individuals | journal = Optometry | volume = 74 | issue = 11 | pages = 695–710 | date = November 2003 | pmid = 14653658 | url = http://www.decp.org/pdfs/nystagmus.pdf | url-status = dead | archive-url = https://web.archive.org/web/20110716064218/http://www.decp.org/pdfs/nystagmus.pdf | archive-date = 16 July 2011 }}</ref> 
* [[obesity]]<ref name="health.harvard.edu" />
* [[epileptic seizure|seizures]]<ref>{{cite book| vauthors = Engel J, Pedley TA, Aicardi J |url= https://books.google.com/books?id=TwlXrOBkAS8C&q=sleep+deprivation+seizure&pg=PA77|title=Epilepsy: A Comprehensive Textbook - Google Books|year=2008|publisher=Lippincott Williams & Wilkins |isbn=978-0-7817-5777-5|access-date=30 January 2015}}</ref>
* [[temper tantrums]] in children<ref name="SleepDep" />
* violent behavior<ref>{{cite journal | vauthors = Vaughn MG, Salas-Wright CP, White NA, Kremer KP | title = Poor sleep and reactive aggression: Results from a national sample of African American adults | journal = Journal of Psychiatric Research | volume = 66-67 | pages = 54–59 | year = 2015 | pmid = 25940021 | doi = 10.1016/j.jpsychires.2015.04.015 }}</ref>
* [[yawn]]ing<ref name="SleepDep" />
* [[mania]]<ref>{{cite journal | vauthors = Wehr TA | title = Sleep-loss as a possible mediator of diverse causes of mania | journal = The British Journal of Psychiatry | volume = 159 | issue = 4 | pages = 576–578 | date = October 1991 | pmid = 1751874 | doi = 10.1192/bjp.159.4.576 | publisher = Bjp.rcpsych.org | s2cid = 22945599 }}</ref>
*[[Sleep inertia]]<ref>{{Cite web|date=20 August 2009|title=Sleep deprivation - Better Health Channel.|url=http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Sleep_deprivation?OpenDocument|archive-url=https://web.archive.org/web/20090820003333/http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Sleep_deprivation?OpenDocument|archive-date=20 August 2009|access-date=24 October 2019}}</ref>
Sleep deprivation may cause symptoms similar to:
* [[attention-deficit hyperactivity disorder]] (ADHD)<ref name="SleepDep" />
* [[psychosis]]<ref name="Ohayon_et_al_1996" /><ref>{{cite web | url = http://ts-si.org/content/view/2634/992/ | title = Neural Link Between Sleep Loss And Psychiatric Disorders | archive-url = https://web.archive.org/web/20090228192413/http://ts-si.org/content/view/2634/992/| archive-date=28 February 2009 | work = ts-si.org | date = 24 October 2007 }}</ref><ref name="sleep_dep">{{cite journal | vauthors = Chan-Ob T, Boonyanaruthee V | title = Meditation in association with psychosis | journal = Journal of the Medical Association of Thailand = Chotmaihet Thangphaet | volume = 82 | issue = 9 | pages = 925–930 | date = September 1999 | pmid = 10561951 }}</ref><ref name="sleep_dep3">{{cite journal | vauthors = Devillières P, Opitz M, Clervoy P, Stephany J | title = [Delusion and sleep deprivation] | journal = L'Encephale | volume = 22 | issue = 3 | pages = 229–231 | date = May–June 1996 | pmid = 8767052 }}</ref>

A 2009 review found that sleep loss had a wide range of cognitive and neurobehavioral effects including unstable attention, slowing of response times, decline of memory performance, reduced learning of cognitive tasks, deterioration of performance in tasks requiring divergent thinking, perseveration with ineffective solutions, performance deterioration as task duration increases; and growing neglect of activities judged to be nonessential.<ref>{{Cite web|url=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3564638/|title=Neurocognitive Consequences of Sleep Deprivation - PMC}}</ref>