An Introduction to Narcolepsy

Narcolepsy is a medical condition that can be found in every racial and ethnic group, and yet remains largely underrecognized and misunderstood. It is a neurological disorder that alters normal sleep patterns. Behind sleep apnea and restless legs syndrome, narcolepsy is the third most diagnosed sleep disorder in the United States, and is estimated to affect over 135,000 Americans. Its symptoms can be severe enough to cause significant problems in a person's professional, social and personal lives, and sometimes diminishes the activities they can participate in.

Narcolepsy is characterized by an inability of the brain to properly regulate sleep-wake cycles. Normally, when a person falls asleep at night, their brain waves slow and become irregular. This is the non-rapid eye movement (NREM) stage of sleep. The next stage is rapid eye movement (REM) sleep, in which the brain waves become more active and dreams generally occur. For narcoleptics, NREM sleep is often bypassed and REM is reached almost immediately upon falling asleep. As a result, narcoleptics often become drowsy and fall asleep uncontrollably and without warning during the day, and wake up frequently during the night. The periods of daytime sleep may range from a few seconds to more than an hour in rare cases.

In addition to excessive daytime sleepiness, or EDS, there are several other major symptoms to narcolepsy. Some individuals experience vivid hallucinations as they are falling asleep or awakening; these are known as hypnogogic hallucinations. Oftentimes these brief daydreams can be quite terrifying for the narcoleptic. Cataplexy, a sudden loss of muscle tone, is another common symptom. These cataplectic attacks fluctuate in length and intensity. Some are barely perceptible, such as a droop in the eyelids, while others are fairly severe. In some cases, individuals lose all muscle stability and completely collapse for a period of time. Cataplexy is usually triggered by strong emotions and impulses such as anger, fear or surprise. It is also often caused by laughter. The person remains conscious throughout the entire episode. Similar to cataplexy is sleep paralysis, in which the person is temporarily unable to move or talk while entering a sleep episode or waking up. This may last from a few seconds to several minutes. EDS, hypnogogic hallucinations, and sleep paralysis can occur in individuals who do not have narcolepsy, but usually just in those who are suffering from a severe lack of sleep. Cataplexy is believed to be exclusive to narcolepsy.

The causes of narcolepsy are still largely unknown. Although researchers have found that certain genotypes are associated with narcolepsy, there is nothing to determine that it is an inherited condition. Individuals may take medication to help offset the effects of narcolepsy, but there is no cure available at this time.