Narcolepsy is a chronic neurological disorder that can begin at any age and continues throughout life. It is a sleep disorder, involving irregular patterns in Rapid Eye Movement (REM) sleep, and significant disruptions of the normal sleep/wake cycle.
Onset typically occurs in pre-teens/teens or the early twenties, but can also happen later in life. Narcolepsy is believed to affect approximately 1 in 2,000 people in the United States. It affects both sexes equally and occurs throughout the world, but is underrecognized and underdiagnosed. Once established, narcolepsy is generally stable and can most often be effectively treated. Lifespan is not affected.
Narcolepsy with cataplexy is caused by the destruction of hypocretin-producing cells in the hypothalamus region of the brain. Hypocretin (also known as orexin) is a neurotransmitter involved in the regulation of the sleep/wake cycle as well as other bodily functions (e.g. blood pressure and metabolism). Narcolepsy with cataplexy is an auto-immune disorder. More research is needed to determine the exact triggers behind narcolepsy without cataplexy.
Diagnosis of narcolepsy is usually confirmed in a sleep lab through a series of tests, which typically includes an overnight polysomnogram (PSG or sleep study) to rule out other causes of EDS and detect any unusual REM patterns. The Multiple Sleep Latency Test (MLST), or daytime nap test, follows, which measures the rapidity of sleep onset and how quickly REM sleep follows. The MLST is the most widely accepted diagnostic test for narcolepsy. A blood test is sometimes used to determine if there is a genetic predisposition towards the disorder. Finally, some research facilities measure the level of hypocretin in the cerebrospinal fluid (CSF). This is rare and only used in certain situations.
The Diagnostic and Statistical Manual (DSM V) divides narcolepsy into Narcolepsy Type 1, or narcolepsy with cataplexy, and Narcolepsy Type 2, or narcolepsy without cataplexy.
Symptoms include:
Excessive Daytime Sleepiness (EDS) is described as a persistent sense of mental cloudiness (brain fog), lack of energy, or extreme exhaustion. It includes daytime sleep attacks that may occur with or without warning and may be uncontrollable, and persistent drowsiness, which can continue for prolonged periods of time. Microsleeps, or fleeting, involuntary moments of sleep that may intrude into the waking state, are also experienced as part of EDS for many people. Naps can help people with narcolepsy (PWNs) feel refreshed for a short period of time before EDS symptoms return.
Cataplexy, the second major symptom of narcolepsy, is nearly unique to the disease. It is a sudden loss of muscle tone, usually triggered by emotions such as laughter, surprise, fear, or anger. Cataplexy occurs while the person is awake and causes feelings of weakness and a loss of voluntary muscle control. Cataplexy may occur more often during times of stress or fatigue. Attacks can involve only a slight feeling of weakness in one part of the body (i.e. sagging facial muscles, nodding head, buckling knees, garbled speech, etc.) or an immediate and total full body collapse. Although someone suffering a severe cataplexy attack may appear unconscious, they are actually awake and alert. Attacks can last from a few seconds up to several minutes. Cataplexy is related to the loss of muscle tone usually associated with dreaming or REM sleep; as protection against acting out one’s dreams, muscles become immobile or paralyzed. In cataplexy, this protection is triggered inappropriately during wakefulness.
Disrupted or fragmented nighttime sleep is sleep disrupted by periods of wakefulness, vivid dreams, sleep talking, and movement. PWNs typically have no difficulty initially falling asleep.
Hypnagogic (during sleep onset) and hypnopompic (during waking) hallucinations are vivid, realistic, and often frightening dreams that occur on the edge of sleep and wakefulness.
Sleep paralysis is the temporary inability to move, occurring in the transition between sleep and wakefulness.
If you think you have narcolepsy, take the Epworth Sleepiness Scale which can help assess daytime sleepiness.