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Narcolepsy and Hypersomnias

Hypersomnias refer to a group of disorders for which excessive daytime sleepiness is the core symptom.  This excessive daytime sleepiness cannot be due to insufficient sleep (sleep deprivation), disturbed nocturnal sleep, insomnia, circadian rhythm disorders, sleep-related breathing (sleep apnea) disorders or medical issues in order to be classified as a hypersomnia or narcolepsy.

The main types of hypersomnias include the following:

Diagnosis of these disorders is made based on clinical symptoms often combined with an overnight sleep study and a daytime nap study called a Multiple Sleep Latency Test.  Further blood tests and cerebrospinal fluid testing may be performed if narcolepsy is suspected.

You can read more about these disorders below.


Narcolepsy is a disorder characterized by excessive daytime sleepiness in addition to other symptoms such as sleep paralysis, cataplexy, hallucinations upon waking or falling asleep, automatic behaviors, difficulty maintaining sleep or disturbed night time sleep, and, often, obesity.  Many of the symptoms of narcolepsy are due to an unusual proclivity to transition rapidly from wakefulness into rapid eye movement (REM) sleep and to experience dissociated REM sleep events.

Excessive daytime sleepiness is usually the most disabling symptom and the first to occur. It is characterized by repeated episodes of naps or lapses into sleep across the daytime. Patients with narcolepsy with cataplexy typically sleep for a short duration and awaken refreshed but within two or three hours begin to feel sleepy again. The pattern repeats itself through the day. Sleepiness is more likely to occur in boring monotonous situations that require no active participation, for example, watching television. Sudden and often irresistible sleep attacks (that is, a sudden onset of sleep or involuntary sleep episodes) may also occur in unusual situations such as eating, walking, or driving.

In cases in which sleepiness is severe, a symptom called “automatic behavior” is occasionally observed: the patient continues an activity in a semiautomatic fashion without memory or consciousness. A patient may, for example, continue to write sentences in a letter or work on the computer, but the output will be nonsensical.

Sleep paralysis is the temporary inability to talk or move when waking; it may last a few seconds to minutes.  Sleep paralysis is also a normal event that many of us have experienced from time to time.  It can be worsened by sleep deprivation.

Hypnagogic hallucinations are vivid, sometimes disturbing dreamlike experiences that occur while dozing, falling asleep and/or upon awakening. These can also occur from time to time in normal individuals.

Cataplexy, a unique characteristic of narcolepsy, is characterized by sudden loss of bilateral muscle tone provoked by strong emotions that are usually positive, such as laughter, pride, elation, or surprise. Negative emotions such as anger may also occasionally be a trigger. Cataplexy can be localized, or it can include all skeletal muscle groups. The lower or upper limbs, neck, mouth, or eyelids may be regionally affected. Affected areas most commonly include the knees, face, and neck. Blurred vision may occur and may reflect oculomotor involvement. Respiratory muscles are never affected, but a feeling of choking may result from the occurrence of cataplexy in an awkward position. The duration of cataplexy is usually short, ranging from a few seconds to several minutes at most, and recovery is immediate and complete.

The diagnosis of narcolepsy can be made clinically without further testing when cataplexy is unequivocally present.  However, if cataplexy is not present or if it is atypical, an overnight sleep study in addition to a daytime Multiple Sleep Latency Test (MSLT) is essential.  An MSLT is a diagnostic sleep test composed of a series of 5 naps the day following an overnight sleep study.  It is used to diagnose hypersomnia and narcolepsy.  A positive test for narcolepsy is comprised of a mean sleep latency (or time it takes to fall asleep) of less than 8 minutes and 2 sleep onset REM periods.  Hypersomnia is diagnosed as a mean sleep latency of less than 8 minutes.  At least 6 hours of sleep on the overnight sleep study as well as lack of other primary sleep disorders such as sleep apnea must be present for an accurate MSLT study.

Treatment of narcolepsy includes a combination of medications and behavioral and lifestyle changes. Medications used to treat narcolepsy include antidepressants, stimulants, ADHD medications and sodium oxybate.

Idiopathic Hypersomnia

Idiopathic Hypersomnia is a condition characterized by excessive sleepiness.  Cataplexy and sleep onset REM periods are absent, distinguishing this condition from narcolepsy.  There are two types of Idiopathic Hypersomnia:

  • Idiopathic Hypersomnia with Long Sleep Time
  • Idiopathic Hypersomnia without Long Sleep Time

Idiopathic hypersomnia with long sleep time is characterized by constant and severe excessive sleepiness with prolonged but unrefreshing naps of up to three or four hours, a prolonged major sleep episode, and great difficulty waking up either in the morning or at the end of a nap. The major sleep episode is prolonged to at least 10 hours (typically 12 to 14 hours) with few or no awakenings. Post-awakening confusion (sleep drunkenness) is often reported. In a research setting, idiopathic hypersomnia with long sleep time is typically diagnosed only in the presence of long sleep time and is a unique disease entity. More recently, the term idiopathic hypersomnia has been used to include subjects with hypersomnolence without increased nocturnal sleep. In the current diagnostic classification, these two variants have been separated.

The major clinical feature of idiopathic hypersomnia without long sleep time is a complaint of constant and severe excessive daytime sleepiness. Daytime sleepiness results in unintended naps that are generally of nonrefreshing nature. Cataplexy is absent. The major sleep episode (e.g., nighttime) is either normal or slightly prolonged (less than 10 hours), usually with few or no awakenings. Patients sometimes have great difficulties waking up in the morning and from naps. Post-awakening confusion (sleep drunkenness) is often reported.

Treatment of idiopathic hypersomnia involves careful attention to contributing factors such as sleep scheduling/hygiene issues, underlying medical disorders, and medications.  Symptoms of Idiopathic hypersomnia may be treated with medications. Medications may include stimulants such as modafinil or amphetamine-like compounds, ADHD medications, antidepressants and sedatives. In case Amphetamine like stimulants can be addictive and lead to tolerance and withdrawal so careful monitoring of these medications is necessary.

RECURRENT HYPERSOMNIA (Including Klein-Levin Syndrome and Menstrual-Related Hypersomnia)

Recurrent hypersomnia is characterized by recurrent episodes of hypersomnia often associated with other symptoms that typically occur weeks or months apart.

The two most well known forms of recurrent hypersomnia are:

  • Klein-Levin Syndrome
  • Menstrual Related Hypersomnia

Menstrual-related Hypersomnia is extremely rare. In this case, hypersomnia reoccurs periodically for one week generally around menses. The use of contraceptive hormone therapy is usually efficacious.

Klein-Levin Syndrome is characterized by a combination of hypersomnia, behavioral, and cognitive changes. Episodes usually last a few days to several weeks and appear one to 10 times a year. Episodes are often preceded by prodromes such as fatigue or headache lasting a few hours. Patients may sleep as long as 16 hours to 18 hours per day, waking or getting up only to eat and void. Urinary incontinence does not occur. Body weight gain of a few kilograms is often observed during the episode. Cognitive abnormalities such as feelings of unreality, confusion, and hallucinations may occur. Behavioral abnormalities such as binge eating, hypersexuality, irritability, and aggressiveness may be present. Patients may respond verbally, but often unclearly or aggressively, when aroused by strong stimuli during the episode. The simultaneous occurrence of all these symptoms is the exception rather than the rule, and in some cases, isolated recurrent hypersomnia may be the only symptom. Amnesia, transient dysphoria, or elation with insomnia may signal the termination of an episode. To be characterized as recurrent hypersomnia, sleep and general behavior must be normal between episodes.

Most cases of Klein-Levin Syndrome occur in teenage boys.  The cause is still unknown.  Episodes generally become less frequent and less severe with time and resolution of the disorder often occurs in early adulthood.

There is no specific treatment or cure for Klein Levin Syndrome.  However, various medications can be used to control symptoms.