He points out that of 521 patients who took the drug in a safety study, 2 had forms of sleep paralysis, which can be a symptom of narcolepsy.

FORBES: Can A Safer Ambien Make Billions? Merck Aims To Find Out

This is a condition that causes the sudden onset of sleep paralysis the loss of muscle tone that occurs when we sleep during waking hours, often as a result of strong emotions.

FORBES: Defending The Narcolepsy 'Date Rape' Drug

Provigil was approved in 1998 to treat narcolepsy, a condition in which patients suffer from constant sleepiness, temporary paralysis and other symptoms brought on by an inability to get adequate sleep.

FORBES: Pay Attention