Hypersomnia is a sleep disorder that is characterized by excessive sleepiness and prolonged periods of sleep. The exact cause of hypersomnia is unknown, but there are several factors that may trigger the disorder. These include medications, neurologic conditions, psychiatric disorders, and sleep deprivation.
Some people with hypersomnia also experience episodes of cataplexy, which is a sudden loss of muscle tone caused by strong emotions such as laughter or surprise. Symptoms of hypersomnia include difficulty falling asleep, difficulty staying asleep, morning headaches, sleepiness during the daytime, and excessive tiredness. Some people with hypersomnia also experience episodes of cataplexy.