Features:
(1) inability to fall asleep at conventional bed-times, despite determined attempts to change
(2) onset of sleep in the early morning (after 02:00)
(3) normal duration of sleep, which often extends into early afternoon if uninterrupted
Problems arise if the person tries to work a normal daytime schedule since the person is sleep deprived.
Complications if attempt to adhere to normal daytime schedules:
(1) daytime sleepiness or cognitive impairment
(2) tardiness at school or work
(3) difficulty in interpersonal relationships
(4) overuse of alcohol and/or sedatives
(5) depression due to problems caused by DSPS
Differential diagnosis:
(1) depression with difficulty falling asleep
(2) other psychiatric disorders
(3) use of caffeine or other stimulants before bedtime
