Sleep deprivation

===Insomnia===
{{Main|Insomnia}}
[[Insomnia]], one of the six types of [[dyssomnia]], affects 21–37% of the adult population.<ref name="UKInsomnia">{{cite journal | vauthors = Morphy H, Dunn KM, Lewis M, Boardman HF, Croft PR | title = Epidemiology of insomnia: a longitudinal study in a UK population | journal = Sleep | volume = 30 | issue = 3 | pages = 274–280 | date = March 2007 | pmid = 17425223 | url = http://www.journalsleep.org/ViewAbstract.aspx?pid=26762 | url-status = live | access-date = 13 December 2015 | archive-url = https://web.archive.org/web/20151222082309/http://www.journalsleep.org/ViewAbstract.aspx?pid=26762 | archive-date = 22 December 2015 }}</ref><ref name="JapanInsomnia">{{cite journal | vauthors = Kim K, Uchiyama M, Okawa M, Liu X, Ogihara R | title = An epidemiological study of insomnia among the Japanese general population | journal = Sleep | volume = 23 | issue = 1 | pages = 41–47 | date = February 2000 | pmid = 10678464 | doi = 10.1093/sleep/23.1.1a | doi-access = free }}</ref><ref>{{Cite journal | vauthors = Rajaee Rizi F, Asgarian FS |date=2022-08-24 |title=Reliability, validity, and psychometric properties of the Persian version of the Tayside children's sleep questionnaire|journal=Sleep and Biological Rhythms |volume=21 |issue=1 |pages=97–103 |language=en |doi=10.1007/s41105-022-00420-6 |pmid=38468908 |s2cid=245863909 |issn=1479-8425|pmc=10899986 }}</ref> Many of its symptoms are easily recognizable, including [[excessive daytime sleepiness]]; frustration or worry about sleep; problems with attention, concentration, or memory; extreme mood changes or irritability; lack of energy or motivation; poor performance at school or work; and tension headaches or stomach aches.

Insomnia can be grouped into primary and secondary, or [[Comorbidity|comorbid]], insomnia.<ref name="WHO">{{cite web|title=Dyssomnias|url=https://www.who.int/selection_medicines/committees/expert/17/application/Section24_GAD.pdf|url-status=live|archive-url=https://web.archive.org/web/20090318104517/http://www.who.int/selection_medicines/committees/expert/17/application/Section24_GAD.pdf|archive-date=18 March 2009|access-date=25 January 2009|publisher=WHO|pages=7–11}}</ref><ref>{{cite journal | vauthors = Buysse DJ | title = Chronic insomnia | journal = The American Journal of Psychiatry | volume = 165 | issue = 6 | pages = 678–686 | date = June 2008 | pmid = 18519533 | pmc = 2859710 | doi = 10.1176/appi.ajp.2008.08010129 | quote = For this reason, the NIH conference [of 2005] commended the term "comorbid insomnia" as a preferable alternative to the term "secondary insomnia." }}</ref><ref>{{Cite journal| vauthors = Erman MK | title = Insomnia: Comorbidities and Consequences | journal = Primary Psychiatry | date = 2007 | volume = 14 | issue = 6 | pages = 31–35 |url=http://www.primarypsychiatry.com/aspx/articledetail.aspx?articleid=1102|url-status=live |archive-url= https://web.archive.org/web/20110715113025/http://www.primarypsychiatry.com/aspx/articledetail.aspx?articleid=1102 |archive-date=15 July 2011|quote=Two general categories of insomnia exist, primary insomnia and comorbid insomnia.}}</ref>

Primary insomnia is a [[sleep disorder]] not attributable to a medical, psychiatric, or environmental cause.<ref>{{cite web|author=World Health Organization|year=2007|title=Quantifying burden of disease from environmental noise|url=http://www.euro.who.int/__data/assets/pdf_file/0005/87638/Noise_EDB_2nd_mtg.pdf|url-status=live|archive-url=https://web.archive.org/web/20101123213411/http://www.euro.who.int/__data/assets/pdf_file/0005/87638/Noise_EDB_2nd_mtg.pdf|archive-date=23 November 2010|access-date=22 September 2010|page=20}}</ref> There are three main types of primary insomnia. These include psychophysiological, idiopathic insomnia, and [[sleep state misperception]] (paradoxical insomnia).<ref name="WHO" /> Psychophysiological insomnia is anxiety-induced. Idiopathic insomnia generally begins in childhood and lasts for the rest of a person's life. It's suggested that idiopathic insomnia is a neurochemical problem in a part of the brain that controls the sleep-wake cycle, resulting in either under-active sleep signals or over-active wake signals. Sleep state misperception is diagnosed when people get enough sleep but inaccurately perceive that their sleep is insufficient.<ref>{{cite journal | vauthors = Lai C, Qiu H | title = Paradoxical Insomnia: Misperception of Sleep Can Be a Tormenting Experience | journal = American Family Physician | volume = 95 | issue = 12 | pages = 770 | date = June 2017 | pmid = 28671423 | url = https://www.aafp.org/afp/2017/0615/p770.html | access-date = 10 May 2020 }}</ref>

Secondary insomnia, or comorbid insomnia, occurs concurrently with other medical, neurological, psychological, and psychiatric conditions. Causation is not necessarily implied.<ref>Biological Rhythms, Sleep and Hypnosis by Simon Green</ref> Causes can be from depression, anxiety, and personality disorders.<ref>{{cite journal | vauthors = McCrae CS, Lichstein KL | title = Secondary insomnia: diagnostic challenges and intervention opportunities | journal = Sleep Medicine Reviews | volume = 5 | issue = 1 | pages = 47–61 | date = February 2001 | pmid = 12531044 | doi = 10.1053/smrv.2000.0146 }}</ref>

Sleep deprivation is known to be cumulative. This means that the fatigue and sleep one lost as a result of, for example, staying awake all night, would be carried over to the following day.<ref>{{Cite web |date=2010-01-20 |title=Sleep Debt: Can You Catch up on Sleep? |url=https://www.sleepfoundation.org/how-sleep-works/sleep-debt-and-catch-up-sleep |access-date=2022-06-27 |website=Sleep Foundation |language=en}}</ref> Not getting enough sleep for a couple of days cumulatively builds up a deficiency and causes symptoms of sleep deprivation to appear. A well-rested and healthy individual will generally spend less time in the [[Rapid eye movement sleep|REM stage]] of sleep. Studies have shown an inverse relationship between time spent in the REM stage of sleep and subsequent wakefulness during waking hours.<ref>{{Cite book| vauthors = Plaford GR |title=Sleep and learning : the magic that makes us healthy and smart|year=2009|isbn=978-1-60709-091-5|location=Lanham | publisher = Rowman & Littlefield Education |oclc=310224798}}</ref> Short-term insomnia can be induced by stress or when the body experiences changes in environment and regimen.<ref>{{Cite web |date=2022-03-24 |title=Insomnia - What Is Insomnia? {{!}} NHLBI, NIH |url=https://www.nhlbi.nih.gov/health/insomnia |access-date=2023-10-19 |website=www.nhlbi.nih.gov |language=en}}</ref>