Delayed Sleep Phase Syndrome:
In delayed sleep phase syndrome, the sleep period is delayed with respect to clock time. As a result sleepiness and sleep onset occur later in the evening and, in turn, alertness and sleep offset occur later in the morning than is conventional. It is one of the circadian rhythm disorders.
Delayed sleep phase syndrome occurs most often in adolescents and young adults. It may be triggered by late light exposure or caffeine use late in the day, but it also tends to run in families and may persist well into adulthood. It can be diagnosed with the use of sleep logs and actigraphy. It can be effectively treated with light box phototherapy, behavioral therapy, and melatonin use.
Example:Chris is a 16-year-old who likes to stay up until 2 a.m. and prefers to sleep in until 10 a.m. on the weekends. During the week, he struggles to get up and has multiple citations for tardiness and often skips his first classes. When he does go to these early classes, he feels extremely tired and performs poorly.
Learn more about circadian rhythm disorders.
American Academy of Sleep Medicine. "International classification of sleep disorders: Diagnostic and coding manual." 2nd ed. 2005.