<Tr> <Th> MeSH </Th> <Td> D021081 </Td> </Tr> <Tr> <Td_colspan="2"> (edit on Wikidata) </Td> </Tr> <P> 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 the general population and relative to 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 . </P> <P> 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 3: 00 am to 12: 00 noon, 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". </P>

I sleep better in the morning than at night