Narcolepsy Sleep Disorder

Narcolepsy affects an estimated 250,000 Americans. People with narcolepsy suffer frequent "sleep attacks" during the day, even if they enjoy a normal amount of night-time sleep. These attacks can last anything from several seconds to more than 30 minutes.

People with narcolepsy may also experience cataplexy (loss of muscle control during emotional situations), hallucinations, temporary paralysis when they awaken, and disrupted night-time sleep. These symptoms seem to be features of REM sleep that appear during waking, which suggests that narcolepsy is a disorder of sleep regulation.

The symptoms of narcolepsy typically appear during adolescence, though it often takes years to obtain a correct diagnosis.

The disorder (or at least a predisposition to it) is usually hereditary, but it is occasionally linked to brain damage from a head injury or to neurological disease.

Once diagnosed, stimulants, antidepressants, or other drugs can help control the symptoms and prevent the embarrassing and dangerous effects of falling asleep at improper times. Naps at certain times of the day may also reduce the excessive daytime sleepiness.

In 1999, a research team working with canine models identified a gene that causes narcolepsy - a breakthrough that brings a cure for this disabling condition within reach.

The gene, hypocretin receptor 2, codes for a protein that allows brain cells to receive instructions from other cells. The defective versions of the gene encode proteins that cannot recognize these messages, perhaps cutting the cells off from messages that promote wakefulness.

The researchers know that the same gene exists in humans, and they are currently searching for defective versions in people with narcolepsy.