Idiopathic hypersomnia

Idiopathic hypersomnia is a type of sleep disorder in which the cause cannot be determined. It is a type of hypersomnia, a class of sleep disorders characterized by excessive daytime sleepiness. This condition causes a number of profound psychological, social, and socioeconomic problems as a person finds their functioning in everyday life compromised by this illness.

Definition & Facts

Hypersomnias are characterized by the inability to feel refreshed from quantities of sleep that are adequate for most of the population. People with this condition feel persistent lethargy and drowsiness. A host of cognitive complaints ensues such as difficulty concentrating and memory impairment.

Idiopathic hypersomnia is a type of primary hypersomnia. That is, it is not a symptom of another condition. Secondary hypersomnias result from diseases and environmental factors such as mental disorders like depression and bipolar disorder, infections, neurodegenerative diseases, and substance abuse.

Examples of primary hypersomnia are narcolepsy and Kleine-Levin syndrome. Those with narcolepsy experience sleep attacks in which they fall involuntarily and suddenly asleep. Kleine-Levin syndrome is a condition in which a person has episodes of extreme hypersomnia as well as hyperphagia and hypersexuality.

Examples of secondary hypersomnia are sleep apnea, a type of sleep-disordered breathing in which a person's airways are obstructed during sleep, resulting in periods in which a person stops breathing while asleep.

Idiopathic hypersomnia is idiopathic in that its causes cannot be determined, though it may be the result of brain damage, infection of undetermined origin, or abnormalities in the production of certain chemicals in the brain that help regulate sleep and wakefulness.

Symptoms & Complaints

This condition can also involve difficulty waking up and the need to use multiple alarm clocks to arouse oneself from sleep. When a person awakens, they may find themselves groggy or sleep drunk, a condition in which a person is neither fully awake nor asleep and experienced disorientation and confusion.

Daily functioning in work, social and family obligations, and participation in recreation and hobbies is severely compromised. A person's productivity on the job is decreased as a result of this condition. He or she may also be increasingly susceptible to workplace injuries or accidents and has an increased risk of causing an automobile accident.

A number of mood disturbances and cognitive problems can ensue. A person may find themselves unable to concentrate on tasks at work or recall visual information or words. Mood swings and irritability may occur. This condition as well as sleep disorders overall are associated with an increased risk of cardiovascular disease including obesity, stroke, blood clots, and heart attack.

Causes

It is unclear what causes idiopathic hypersomnia though theories exist. Unlike secondary forms of hypersomnia, it is not caused by another diagnosed medical condition nor have genetic factors been identified. It is theorized that infections, brain damage, and brain abnormalities are causal factors.

Research studies at Emory have discovered that the effects of the brain chemical, GABA (gamma-aminobutyric acid) are increased among those with this condition. This brain chemical's effects are influenced and compounded by sedatives like alcohol and benzodiazepines. The chemical that increases the effects of GABA has not been identified.

Diagnosis & Tests

Diagnosing this condition involves ruling out other sleep disorders, neurological disorders, substance-related problems and mental disorders.

Standard diagnostic procedures such as taking a medical history, family history, and performing a physical examination will occur. An inquiry into the patient's medications and drug use will need to be thorough. Various blood tests will be undertaken to rule out anemia, hypothyroidism, and hormonal imbalances which can lead to hypersomnia.

The Epworth Sleepiness Scale is a questionnaire that establishes a patient's level of sleepiness during different activities or in different contexts. Neurological evaluations and psychiatric evaluations can help establish a patient's symptoms as well as rule out neurological and mental disorders as underlying causes. A psychomotor vigilance test may be performed; this measures a person's reaction time to test their alertness.

Polysomnograms or sleep studies will be conducted. These are generally taken overnight and involve monitoring the body's functions such as heart rate, brain wave activity via electroencephalography, breathing, as well as any unusual movements the body makes.

Multiple sleep latency tests may also be conducted. This is a type of test where a person is placed in a quiet, relaxing context conducive to sleep. How quickly they fall asleep after initiating the napping process is measured.

Lumbar punctures or spinal taps may be performed to assess the cerebrospinal fluid for the presence of lowered levels of hypocretin, which would indicate narcolepsy. Hypocretin regulates wakefulness as well as appetite. It is a neuropeptide.

Imaging tests may be performed to assess any structural or functional abnormalities of the brain. These could include computed tomography (CT) scans, magnetic resonance imaging (MRI) scans, and single-photon emission computed tomography (SPECT).

Treatment & Therapy

Treatment for idiopathic hypersomnia is difficult because its causes are unknown. Various medications may be prescribed to increase wakefulness. These are typically stimulants such as modanifil and amphetamine. Many stimulants can be habit-forming or can cause tolerance, which mitigates their efficacy over a period of time.

Cognitive behavioral therapy is a form of psychotherapy that may be able to assist in helping patients establish proper sleep hygiene routines. Exposure to light at appropriate times may help people with sleep disorders generally.

Flumazenil is a drug whose efficacy in treating idiopathic hypersomnia is being studied in clinical trials. It is a GABA receptor antagonist and is typically used to counteract the effects of sedatives like benzodiazepine. This drug may inhibit the brain chemicals promoting sleepiness. As opposed to stimulating the central nervous system, flumazenil counteracts the sedating effects of brain chemicals.

Prevention & Prophylaxis