Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Narcolepsy is a chronic sleep disorder, or dyssomnia, characterized by excessive sleepiness and sleep attacks at inappropriate times, such as while at work. People with narcolepsy often experience disturbed nocturnal sleep and an abnormal daytime sleep pattern, which often is confused with insomnia. Learn more about narcolepsy, its causes, symptoms and possible treatments in the following pages.