CIRCADIAN RHYTHM DISORDERS
This category of disorders includes conditions in which the sleep times are out of alignment. A patient with one of these disorders does not follow the normal sleep times at night.
Delayed Sleep-Wake Phase This circadian rhythm disorder is a sleep pattern that is delayed by two or more hours so that a person goes to sleep later at night and sleeps later in the morning.
Advanced Sleep-Wake Phase
This circadian disorder causes people to fall asleep several hours before a normal bedtime and wake up hours earlier than most people wake in the morning.
Irregular Sleep-Wake Rhythm
This disorder causes a person's circadian rhythms to be so disorganized that there is no clear sleep or wake pattern. People with this sleep disorder may sleep off and on in a series of naps over a 24-hour period.
Non-24-Hour Sleep-Wake Rhythm
Non-24 is a sleep disorder that causes a person's sleep time to shift a little later every day. Sleep times may go in and out of alignment with other people over time.
A non-traditional work schedule involving shifts that occur when most people are sleep can cause shift work disorder. The condition causes your sleep to be poor and consistent feelings of fatigue or exhaustion.
Jet lag occurs when you travel across multiple time zones and have difficulty adjusting to the new schedule.