Hypersomnia is a sleep disorder that causes people to feel extremely sleepy throughout the day. Patients with hypersomnia also sleep for long periods at night and may nap repeatedly during the day. However, the sleep patients receive does not leave them feeling refreshed or more alert.

There are two main categories of hypersomnia. Primary hypersomnia does not have a known cause and is a chronic condition. Secondary hypersomnia may be traced to medical conditions (e.g., narcolepsy), physical injury and use of certain medications (e.g., tranquilizers).

Hypersomnia is considered to be a less common sleep disorder than insomnia, which involves difficulty falling asleep or staying asleep. Hypersomnia is most likely to first occur in people during adolescence and young adulthood.

In diagnosing hypersomnia, a physician may pay particular attention to details such as how much sleep a patient gets each night and whether or not excessive napping occurs. In some cases, a physician may order a sleep study (polysomnography) in which a person’s brain waves and other physiological responses are measured during a typical sleep cycle.

In many cases, hypersomnia is treated with medications. This may include psychostimulants and amphetamines. Certain lifestyle and dietary changes may also be recommended for patients with hypersomnia. However, patients with hypersomnia may continue to require above-average levels of sleep, even with treatment and lifestyle changes.

Other treatment methods may be recommended if a specific medical condition or other cause is found to be responsible for a patient’s hypersomnia.

There is no known way to prevent primary hypersomnia (in which a cause is not identified). Preventing secondary hypersomnia (in which a cause is identified) involves taking steps to prevent its cause. For example, losing weight may help prevent sleep disorders such as hypersomnia in patients who are obese.