Delayed sleep phase syndrome (DSPS) is a fairly common disorder of sleep timing. People with DSPS tend to fall asleep at very late times, and also have difficulty waking up in time for normal work, school, or social needs. People with DSPS and their families can find here a description of the syndrome, an overview of treatment methods, and resources. biologicalchronobiologycycledspsinsomnialightmelatoninnightnightowlowlrhythmssleep-waketherapy with delayedphasesleepsyndrome