Characterized by periods of intense fear of the discomfort associated with chest pain, rapid and pounding heartbeats, and sweating that unexpectedly occur, it afflicts two percent of all Americans.

Polysomnographic monitoring demonstrates an abrupt awakening with a sensation of panic out of Stage 2 or 3 sleep—and more rarely, the attack is triggered at sleep onset. The patient is subsequently hyperaroused and has difficulty returning to sleep. Most patients have daytime panic attacks and symptoms of agoraphobia characterized by a fear of being in places or situations from which escape is difficult or embarrassing.

Common situations include being alone, in a crowd, on a bridge, or traveling in a bus, train or car. Two to three times more common in women than men, the average age of onset is in the late twenties. Panic Disorder tends to run in families.