Delayed sleep phase

Delayed sleep phase disorder (DSPD), more often known as delayed sleep phase syndrome and also as delayed sleep–wake phase disorder, is a chronic dysregulation of a person's circadian rhythm (biological clock), compared to those of the general population and societal norms. The disorder affects the timing of sleep, peak period of alertness, the core body temperature rhythm, and hormonal and other daily cycles. People with DSPD generally fall asleep some hours after midnight and have difficulty waking up in the morning. People with DSPD probably have a circadian period significantly longer than 24 hours. Depending on the severity, the symptoms can be managed to a greater or lesser degree, but no cure is known, and research suggests a genetic origin for the disorder. Affected people often report that while they do not get to sleep until the early morning, they do fall asleep around the same time every day. Unless they have another sleep disorder such as sleep apnea in addition to DSPD, patients can sleep well and have a normal need for sleep. However, they find it very difficult to wake up in time for a typical school or work day. If they are allowed to follow their own schedules, e.g. sleeping from 4:00 am to 1:00 pm, their sleep is improved and they may not experience excessive daytime sleepiness. Attempting to force oneself onto daytime society's schedule with DSPD has been compared to constantly living with jet lag; DSPD has, in fact, been referred to as 'social jet lag'. Researchers in 2017 linked DSPD to at least one genetic mutation. The syndrome usually develops in early childhood or adolescence. An adolescent version may disappear in late adolescence or early adulthood; otherwise, DSPD is a lifelong condition. The best estimate of prevalence among adults is 0.13–0.17% (1 in 600). Prevalence among adolescents is as much as 7–16%. DSPD was first formally described in 1981 by Elliot D. Weitzman and others at Montefiore Medical Center. It is responsible for 7–13% of patient complaints of chronic insomnia. However, since many doctors are unfamiliar with the condition, it often goes untreated or is treated inappropriately; DSPD is often misdiagnosed as primary insomnia or as a psychiatric condition. DSPD can be treated or helped in some cases by careful daily sleep practices, morning light therapy, evening dark therapy, earlier exercise and meal times, and medications such as melatonin and modafinil; the former is a natural neurohormone partly responsible for the human body clock. At its most severe and inflexible, DSPD is a disability. A chief difficulty of treating DSPD is in maintaining an earlier schedule after it has been established, as the patient's body has a strong tendency to reset the sleeping schedule to its intrinsic late times. People with DSPD may improve their quality of life by choosing careers that allow late sleeping times, rather than forcing themselves to follow a conventional 9-to-5 work schedule. In the DSPD cases reported in the literature, about half of the patients have suffered from clinical depression or other psychological problems, about the same proportion as among patients with chronic insomnia. According to the ICSD: A direct neurochemical relationship between sleep mechanisms and depression is another possibility. DSPD may cause excessive or inappropriate production of melatonin. Serotonin, a mood regulator, is the precursor of melatonin. As a result, increased endogenous melatonin production can deplete serotonin levels and may cause depression. It is conceivable that DSPD has a role in causing depression because it can be such a stressful and misunderstood disorder. A 2008 study from the University of California, San Diego found no association of bipolar disorder (history of mania) with DSPD, and it states that The fact that half of DSPD patients are not depressed indicates that DSPD is not merely a symptom of depression. Sleep researcher Michael Terman has suggested that those who follow their internal circadian clocks may be less likely to suffer from depression than those trying to live on a different schedule.