A recognized sleep disorder which accounts for about 40% of all occurances of sleep disorders, even though some are misdiagnosed as insomnia. A person suffering from the disorder finds it difficult to match the normal sleeping habits of their society; for example, a sufferer may naturally drift towards a cycle of sleeping at 2 AM and waking at 10 AM. Often, a sufferer earns the reputation of being a "night owl" or simply "not a morning person." This last issue is a key issue, as sufferers may find it difficult to meet societal expectations (e.g. functioning at work or school).

It is theorized that DSPD is caused by a disturbance between the patient's biological clock and surrounding environmental cues. As society becomes less connected to nature, we can expect to see even more occurances of this disorder.

It may also be a natural occurance; in primates, a few in every tribe are inexplicably nocturnal, even though they are a burden on the tribe (as they are unable to hunt alone). Perhaps it is actually an evolutionary advantage; by maintaining a nocturnal population, the tribe always has a few night guards who can raise an alarm if an enemy approaches by night.

DSPS, or 'Delayed Sleep Phase Syndrome', usually occurs after adolescence or late childhood. It is also known as phase lag syndrome

What is it?

This syndrome is one of many types of insomnia and usually occurs after a lengthy period of late-night parties and studying/coding/hacking sessions. Even after a you return to a normal day schedule you may find you're unable to sleep at normal hours. The problem is that the major sleep episode has shifted, which leads to complaints of insomnia, being unable to sleep or wake up when you want to. Scientifically: the syndrome is a shift in the circadian rythm


Patients usually fall asleep after 2am, have trouble or unable to wake up during the work/school weeks and wake up late (10am to 3pm) in the weekends. They find ordinary methods like sleeping pills and going to bed early have little or no effect at all. They usually think of themselves as night-people.


There are some known treatments, but success varies. These are mainly chronotherapy, bright light therapy and some natural medications like melatonine. Improving sleeping hygiene (clean room, no background sounds except white noise etc) is also reported to be effective in some cases.

DSPS can be diagnosed if this pattern persists over three months and the major sleep episode has shifted over 2 hours a day. But is rarely diagnosed for people of 30 years of age

Just like with other types of insomnia about 50% of the patients suffer from psychiatric problems like depression.

Thanks to wertperch and Lord Brawl for their help and suggestions

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