Hypersomnia

Hypersomnia is a substantial increase in total sleeping time.

Hypersomnia, which is less common than insomnia, refers to an increase of at least 25% in total sleeping time that continues for more than a few days. Hypersomnia does not refer to sleeping substantially more for a few nights or days after a period of sleep deprivation or unusual physical exertion. In such circumstances, extra sleep is a normal response.

Hypersomnia may indicate a serious disorder such as a neurologic disorder (for example, encephalitis, meningitis, or a brain tumor), a heart or lung disorder, or liver failure. Hypersomnia may also be a symptom of sleep apnea or a psychologic disorder (such as severe anxiety or depression). Chronic hypersomnia that begins during adolescence may be a symptom of narcolepsy. Hypersomnia may also result from overuse of sleep aids.

When evaluating a person who has become excessively sleepy, doctors ask about the person's mood, sleep-wake schedule, and use of drugs. Often, a sleep partner can describe the person's sleep abnormalities best. These abnormalities may include snoring and breathing pauses (which suggest obstructive sleep apnea) as well as grinding of teeth, kicking, and sleepwalking. Doctors may evaluate the heart, lungs, and liver to determine whether a disorder is causing hypersomnia. A neurologic examination may also be necessary (see Section 6, Chapter 77). It may detect impaired memory or other problems suggesting a neurologic disorder. If a neurologic disorder is suspected, computed tomography (CT) or magnetic resonance imaging (MRI) is performed, and the person is referred to a neurologist.