What is excessive daytime sleepiness?

Excessive daytime sleepiness is a common problem of adolescence, and it is usually caused by insufficient sleep, but may be associated with serious conditions such as narcolepsy, (falling asleep suddenly many times during the day), sleep apnea or the delayed sleep phase syndrome (an inability to fall asleep until 3 or 4 am, and trouble getting out of bed in the morning). Treatment for delayed sleep phase syndrome includes encouraging good sleep habits, strict scheduling, phototherapy, and sometimes medication.