Definition of Irregular sleep-wake syndrome:

Irregular sleep-wake syndrome is sleeping without any real schedule.

Causes, incidence, and risk factors:

Some people have an irregular sleep-wake pattern because of a problem with brain function, the body's internal clock (circadian pacemaker), or other reasons.

This disorder is very uncommon. It typically occurs in someone with a brain dysfunction who does not have a regular routine during the day. The amount of total sleep time is normal, but the body clock loses its normal circadian cycle.

Similar symptoms may be seen in people who have frequently changing work shifts and in travelers who often change time zones. These people have a different condition, such as shift work sleep disorder or jet lag syndrome.