Hypersomnia is a substantial increase in total sleeping time. Excessive daytime sleepiness (EDS) is the inability to stay awake and alert during the day, resulting in unintended lapses into drowsiness or sleep.
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. EDS refers to a condition in which people are abnormally sleepy during the day. They may fall asleep while they are driving or working. In some disorders, such as narcolepsy, hypersomnia and EDS occur together in the same person. In other disorders, such as sleep deprivation, the two do not occur together.
Being unusually sleepy and falling asleep unintentionally after a period of sleep deprivation is not hypersomnia. In such cases, extra sleep is a desired response. However, hypersomnia and EDS in people who have not previously curtailed their sleep may indicate a serious disorder, such as the following:
Chronic hypersomnia that begins during adolescence may be a symptom of narcolepsy. Hypersomnia may also result from overuse of sleep aids and other drugs that cause drowsiness.
When evaluating people who have become excessively sleepy, doctors ask about their mood, sleep-wake schedule, use of drugs, and any abnormalities that occur during sleep. These abnormalities may include snoring and breathing pauses (which suggest obstructive sleep apnea), as well as grinding of teeth and kicking during sleep. Often, a sleep partner can describe the sleep abnormalities best. Doctors also do a physical examination.
Depending on other symptoms and the results of the physical examination, doctors may evaluate the heart, lungs, and liver to determine whether a disorder is causing hypersomnia. A neurologic examination may also be necessary (see Symptoms and Diagnosis of Brain, Spinal Cord, and Nerve Disorders: Physical Examination.). 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 done, and the person is referred to a neurologist. In many cases, people with hypersomnia and EDS require polysomnography with or without multiple sleep latency testing to establish the proper diagnosis.
The treatment of hypersomnia with or without EDS depends on the underlying diagnosis. If doctors determine that the person has “idiopathic hypersomnia,” that is, hypersomnia without a specific underlying cause, they often recommend proper sleep habits and regular naps. In more severe cases, stimulant drugs, such as modafinil and sometimes amphetamine, dextroamphetamine, or methylphenidate, are used to help reduce the sleepiness. If EDS and hypersomnia are caused by another condition, such as sleep apnea syndrome, a brain infection, or depression, that condition is treated.
Last full review/revision March 2008 by Karl Doghramji, MD