Delayed sleep-phase syndrome (DSPS) is a chronic disorder of sleep timing. People with DSPS tend to fall asleep at very late times, and also have difficulty waking up in the morning.

the key characteristics of DSPS are:

1. Sleep-onset and wake times that are intractably later than desired
2. Actual sleep-onset times at nearly the same daily clock hour
3. Little or no reported difficulty in maintaining sleep once sleep has begun
4. Extreme difficulty awakening at the desired time in the morning
5. A relatively severe to absolute inability to advance the sleep phase to earlier hours by enforcing conventional sleep and wake times.

Attempting to force oneself through 9–5 life with DSPS has been compared to constantly living with 6 hours of jet lag. Often, sufferers manage only a few hours sleep a night during the working week, then compensate by sleeping until the afternoon on weekends. Sleeping in on weekends, and/or taking long naps during the day, gives the DSPS patient relief from daytime sleepiness but also perpetuates the late sleep phase.

People with DSPS tend to be extreme night owls. They feel most alert and say they function best and are most creative in the evening and at night. DSPS patients cannot simply force themselves to sleep early. They may toss and turn for hours in bed, and sometimes not sleep at all, before reporting to work or school.

By the time DSPS patients seek medical help, they usually have tried many times to change their sleeping schedule. Failed tactics to sleep at earlier times may include relaxation techniques, early bedtimes, hypnosis, alcohol, sleeping pills, dull reading, and home remedies. DSPS patients who have tried using sedatives at night often report that the medication makes them feel tired or relaxed, but that it fails to induce sleep. They often have asked family members to help wake them in the morning, or they have used several alarm clocks. As the syndrome is most common in adolescence, it is often the patient's parents who initiate seeking help, after great difficulty waking their child or teenager in time for school.