Obesity, especially if it causes obstructive sleep apnea
When no cause for the sleepiness can be found, it is called idiopathic hypersomnia.
PROBLEMS STICKING TO A REGULAR SLEEP SCHEDULE
Problems may also occur when you do not stick to a regular sleep and wake schedule. This occurs when people travel between time zones and with shift workers who are on changing schedules, especially nighttime workers.
Disorders that involve a disrupted sleep schedule include:
Irregular sleep-wake syndrome
Jet lag syndrome
Paradoxical insomnia (the person sleeps a different amount than they think they do)
Shift work sleep disorder
Abnormal behaviors during sleep are called parasomnias. They are fairly common in children and include: