Kleine-Levin syndrome

Kleine-Levin Syndrome, or KLS, is a rare sleep disorder characterized by episodes of near-constant sleep (up to 20 hours per day) and altered behavior. Many of the symptoms are also common among other sleep disorders (ie., irritability, lack of energy, etc.), but onset differently due to the unique nature of KLS. The disorder first presents in adolescence and affects mostly boys. Symptoms are temporary, lasting from days to weeks, and sufferers are otherwise normal between attacks. Its cause is not known.