Editing Sleep disorder (section)

=== 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" />