These changes could be used to detect those most at risk of developing AD. However, this is still only theoretical. While the exact mechanisms and the causal relationship between sleep disturbances and AD remains unclear, these findings already provide a better understanding and offer possibilities to improve targeting of at-risk populations—and the implementation of treatments to curb the cognitive decline of AD patients. 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. Sleep disturbances - insomnia, hypersomnia and delayed sleep-phase disorder - are quite prevalent in severe mental illnesses such as psychotic disorders. 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. 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). 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.
Its prevalence among men is 15.9%, while 18.9% of women experience it. When considering specific populations, 28.3% of students and 31.9% of psychiatric patients have experienced this phenomenon at least once in their lifetime. Of those psychiatric patients, 34.6% have panic disorder. Sleep paralysis in students is slightly more prevalent for those of Asian descent (39.9%) than other ethnicities (Hispanic: 34.5%, African descent: 31.4%, Caucasian 30.8%). Restless leg syndrome
According to one meta-analysis, the average prevalence rate for North America and Western Europe is estimated to be 14.5±8.0%. Specifically in the United States, the prevalence of restless leg syndrome is estimated to be between 5% and 15.7% when using strict diagnostic criteria. RLS is over 35% more prevalent in American women than their male counterparts. See also
References
External links

 Media related to Sleep disorders at Wikimedia Commons
Sleep Problems – information leaflet from mental health charity The Royal College of Psychiatrists
WebMD Sleep Disorders Health Center