Editing Sleep disorder (section)

== Sleep disorder symptoms in psychiatric illnesses ==

=== Schizophrenia ===
In individuals with psychiatric illnesses sleep disorders may include a variety of clinical symptoms, including but not limited to: excessive daytime sleepiness, difficulty falling asleep, difficulty staying asleep, nightmares, sleep talking, sleepwalking, and poor sleep quality.<ref name=":19">{{cite journal | vauthors = Hombali A, Seow E, Yuan Q, Chang SH, Satghare P, Kumar S, Verma SK, Mok YM, Chong SA, Subramaniam M | display-authors = 6 | title = Prevalence and correlates of sleep disorder symptoms in psychiatric disorders | journal = Psychiatry Research | volume = 279 | pages = 116–122 | date = September 2019 | pmid = 30072039 | doi = 10.1016/j.psychres.2018.07.009 | doi-access = free }}</ref> Sleep disturbances - insomnia, hypersomnia and delayed sleep-phase disorder - are quite prevalent in severe mental illnesses such as psychotic disorders.<ref name=":22">{{cite journal | vauthors = Laskemoen JF, Simonsen C, Büchmann C, Barrett EA, Bjella T, Lagerberg TV, Vedal TJ, Andreassen OA, Melle I, Aas M | display-authors = 6 | title = Sleep disturbances in schizophrenia spectrum and bipolar disorders - a transdiagnostic perspective | journal = Comprehensive Psychiatry | volume = 91 | pages = 6–12 | date = May 2019 | pmid = 30856497 | doi = 10.1016/j.comppsych.2019.02.006 | doi-access = free | hdl = 10852/76588 | hdl-access = free }}</ref> In those with [[schizophrenia]], sleep disorders contribute to cognitive deficits in learning and memory. Sleep disturbances often occur before the onset of psychosis.

Sleep deprivation can also produce hallucinations, delusions and depression.<ref name="Pocivavsek">{{cite journal | vauthors = Pocivavsek A, Rowland LM | title = Basic Neuroscience Illuminates Causal Relationship Between Sleep and Memory: Translating to Schizophrenia | journal = Schizophrenia Bulletin | volume = 44 | issue = 1 | pages = 7–14 | date = January 2018 | pmid = 29136236 | pmc = 5768044 | doi = 10.1093/schbul/sbx151 }}</ref> A 2019 study investigated the three above-mentioned sleep disturbances in schizophrenia-spectrum (SCZ) and bipolar (BP) disorders in 617 SCZ individuals, 440 BP individuals, and 173 healthy controls (HC). Sleep disturbances were identified using the Inventory for Depressive Symptoms - clinician rated scale (IDS-C).<ref name=":22" /> Results suggested that at least one type of sleep disturbance was reported in 78% of the SCZ population, in 69% individuals with BD, and in 39% of healthy controls.<ref name=":22" /> The SCZ group reported the most number of sleep disturbances compared to the BD and HC groups; specifically, hypersomnia was more frequent among individuals with SCZ, and delayed sleep phase disorder was three times more common in the SCZ group compared to the BD group.<ref name=":22" /> Insomnias were the most frequently reported sleep disturbance across all three groups.<ref name=":22" />

=== Bipolar disorder ===
One of the main behavioral symptoms of [[bipolar disorder]] is abnormal sleep. Studies have suggested that 23-78% of individuals with bipolar disorders consistently report symptoms of excessive time spent sleeping, or hypersomnia.<ref name=":19" /> The pathogenesis of bipolar disorder, including the higher risk of suicidal ideation, could possibly be linked to circadian rhythm variability, and sleep disturbances are a good predictor of mood swings.<ref name=":20">{{cite journal | vauthors = Steardo L, de Filippis R, Carbone EA, Segura-Garcia C, Verkhratsky A, De Fazio P | title = Sleep Disturbance in Bipolar Disorder: Neuroglia and Circadian Rhythms | journal = Frontiers in Psychiatry | volume = 10 | pages = 501 | date = 2019-07-18 | pmid = 31379620 | pmc = 6656854 | doi = 10.3389/fpsyt.2019.00501 | doi-access = free | author-link5 = Alexei Verkhratsky }}</ref> The most common sleep-related symptom of bipolar disorder is insomnia, in addition to hypersomnia, nightmares, poor sleep quality, OSA, extreme daytime sleepiness, etc.<ref name=":20" /> Moreover, animal models have shown that sleep debt can induce episodes of bipolar mania in laboratory mice, but these models are still limited in their potential to explain bipolar disease in humans with all its multifaceted symptoms, including those related to sleep disturbances.<ref>{{cite journal | vauthors = Logan RW, McClung CA | title = Animal models of bipolar mania: The past, present and future | journal = Neuroscience | volume = 321 | pages = 163–188 | date = May 2016 | pmid = 26314632 | pmc = 4766066 | doi = 10.1016/j.neuroscience.2015.08.041 }}</ref>

=== Major depressive disorder (MDD) ===
Sleep disturbances (insomnia or hypersomnia) - though not a necessary diagnostic criterion - are one of the most frequent symptoms of individuals with major depressive disorder (MDD).<ref>{{cite journal | vauthors = Liu X, Buysse DJ, Gentzler AL, Kiss E, Mayer L, Kapornai K, Vetró A, Kovacs M | display-authors = 6 | title = Insomnia and hypersomnia associated with depressive phenomenology and comorbidity in childhood depression | journal = Sleep | volume = 30 | issue = 1 | pages = 83–90 | date = January 2007 | pmid = 17310868 | doi = 10.1093/sleep/30.1.83 | doi-access = free }}</ref> Among individuals with MDD, insomnia and hypersomnia have prevalence estimates of 88% and 27%, respectively, whereas individuals with insomnia have a threefold increased risk of developing MDD.<ref name=":21">{{cite journal | vauthors = Murphy MJ, Peterson MJ | title = Sleep Disturbances in Depression | journal = Sleep Medicine Clinics | volume = 10 | issue = 1 | pages = 17–23 | date = March 2015 | pmid = 26055669 | pmc = 5678925 | doi = 10.1016/j.jsmc.2014.11.009 }}</ref> Depressed mood and sleep efficiency strongly co-vary, and while sleep regulation problems may precede depressive episodes, such depressive episodes may also precipitate sleep deprivation.<ref name=":21" /> Fatigue, as well as sleep disturbances such as irregular and excessive sleepiness, are linked to symptoms of depression.<ref name=":21" /> Recent research has even pointed to sleep problems and fatigues as potential driving forces bridging MDD symptoms to those of co-occurring generalized anxiety disorder.<ref name="Coussement & Heeren-2022">{{cite journal | vauthors = Coussement C, Heeren A | title = Sleep problems as a transdiagnostic hub bridging impaired attention control, generalized anxiety, and depression | journal = Journal of Affective Disorders | volume = 296 | pages = 305–308 | date = January 2022 | pmid = 34606807 | doi = 10.1016/j.jad.2021.09.092 | s2cid = 238357084 }}</ref>