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Idiopathic Hypersomnia

Idiopathic Hypersomnia

The Question

Some Facts on Sleep

Physiology Normal Sleep

Primary Hypersomnia

Idiopathic hypersomnia

Management of Sleeping Disorders

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The Question: "…My friend suffers from idiopathic hypersomnia. Please let us know about this condition. "

Dr. Keti:
July 15, 2003

Some Facts on Normal Sleeping Process
Sleep is a dynamic process, during which the brain is very active. There are recognized stages of sleep, each of which exhibits different type of brain wave activity. Generally, sleep is divided in five different stages, that cycle repeatedly during a single night's rest. The stages are numbered as one, two, three, four and REM (rapid eye movement) stage. Stages 1 through 4 are known as non-rapid eye movement sleep (NREM). It is believed that about 50% of our sleeping time is spent in stage two and about 20% in REM stage. A complete sleep cycle, usually takes about an hour and a half and an adult normally sleeps more than 2 hours a night in REM. A complete sleep cycle, from the beginning of stage 1 to the end of REM usually takes about an hour and a half. An adult normally sleeps more than 2 hours a night in REM.

Sleep Disorders in General
According to the National Institute of Neurological Disorders and Stroke, about 40 million Americans suffer each year from some sort of chronic sleep disorder.
Many different sleep disorders are generally classified into three categories:
· Lack of sleep, or insomnias;
· Disturbed sleep, such as obstructive sleep apnea; and
· Too much sleep, as in narcolepsy. You can read more here Sleep Disorders

Primary Hypersomnia
Patients with primary hypersomnia usually present with complaints of long but non-refreshing sleep over nighttime, difficulty awakening (referred to as sleep drunkenness), daytime sleepiness and intellectual dysfunction. Some often report frequent headaches and Raynaud's phenomena. Previously called non-REM narcolepsy, this relatively rare disorder is represented by up to 10% of patients reportedly suffering from hypersomnia.
The diagnosis is based on polysomnographic test findings of hypersomnia, as subjective complaints of excessive sleepiness are not sufficient for diagnostic purposes. In some cases family history of excessive sleepiness may be present. The diagnosis of primary hypersomnia includes presence of recurrent forms of excessive sleepiness of at least 3 days' duration occurring several times a year for at least 2 years. One known syndrome among the recurrent or intermittent hypersomnia disorders is the Kleine-Levin syndrome, mainly seen in adolescent boys; another is the menstrual cycle-associated hypersomnia syndrome. In addition to hypersomnia, patients with Kleine-Levin syndrome are known to often demonstrate aggressive or inappropriate sexuality, compulsive overeating, and other somewhat bizarre behaviors. The rare nature of this syndrome and its behaviors may be mistaken for psychosis, malingering, or a personality disorder. It is worth noticing that the frequency and importance of hypersomnia and daytime sleepiness in otherwise healthy individuals have been increasingly recognized (ref. 1, 2)

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Idiopathic hypersomnia
This disorder is considered to be a neurological disorder in which nocturnal sleep is prolonged but not refreshing. Daytime naps may be long and unsatisfactory. Patients may sleep for periods of up to 20 hours a day. PSG or Polysomnography Test shows a relatively normal sleep pattern. The PSG is an all-night sleep study. The multiple sleep latency test (MSLT) demonstrates pathological sleepiness, but REM sleep does not occur during the two or more naps. Hypersomnia may also be secondary to medical conditions such as viral infections, especially mononucleosis and encephalitis, or hydrocephalus. It is usually necessary to obtain a PSG in order to distinguish among the disorders leading to EDS.

Many conditions can cause excessive sleepiness; therefore, sleep studies are generally required for accurate diagnosis.

One of these studies, the Nocturnal Polysomnography can determine the presence and severity of sleep disorders such as sleep apnea, periodic limb movements, and nocturnal sleep disturbance. Another test called Multiple Sleep Latency Test (MSLT), usually performed the following day, provides a measure of the severity of sleepiness and an indication of the presence or absence of early onset of Rapid Eye Movement(REM) sleep. In narcolepsy, the presence of two or more sleep-onset REM periods during the four to five nap periods is sufficient for diagnostic purposes. However, this finding is not specific. Other causes of early-onset REM sleep may include circadian rhythm disturbances, REM sleep deprivation, sleep disturbance from sleep apnea or other disorders, and drug or alcohol withdrawal. Some patients with brain pathology in areas concerned with sleep regulation also may have early onset of REM sleep.

Management of Sleeping Disorders
Medications and behavioral measures are designed to enhance alertness during critical times of the day such as at work, during school, and while driving. Medical doctors also emphasize the importance of good sleep and the risks associated with sleepiness while driving. Naps during lunch or other breaks are often helpful. Stimulants such as methylphenidate, dextroamphetamine, and pemoline improve alertness in most narcoleptics. It is recommended that stimulants be initiated at low doses and increased gradually until symptoms are controlled or side effects appear. In general, the lowest effective dose should be used, but some patients may not recognize the severity of their sleepiness and reports from family members should also be obtained to assess the effectiveness of treatment. It is also widely believed that the risk for amphetamine abuse is no higher among narcoleptics than in other population groups. (ref.3)

Your doctor should help you exclude known conditions that are related to sleep disorders.
Appropriate treatment might include some changes in your lifestyle, physical and social activities in addition to any medication that you may have to take.

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References and Links

Primary Hypersomnia


NINDS Hypersomnia Information Page


Excessive Daytime Sleepiness (EDS)

Mental Health - PsychNet-UK

The Merck Manual- article

Sleep Disorder


1. Rothstein JD, Guidotti A, Tinuper P, et al: Endogenous benzodiazepine receptor ligands in idiopathic recurring stupor. Lancet 1992; 340:1002-1004. (ref. 1)

2. Mignot E, Wang C, Rattazzi C, et al: Genetic linkage of autosomal recessive canine narcolepsy with a mu immunoglobulin heavy-chain switch-like segment. Proc Natl Acad Sci U S A 1991; 88:3475-3478.(ref. 2)

3. Goetz: Textbook of Clinical Neurology, 1st Ed (ref. 3)

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