Narcolepsy is a disorder of the central nervous system that is characterized by sudden, recurring attacks of sleep. Although narcolepsy was first described in the human medical literature over ninety years ago, the first case of canine narcolepsy was recognized in 1973. It currently has been reported in several breeds of dogs, in cats, and in horses. It is a well defined neurological condition in human beings, afflicting as many as five to ten people out of every 10,000.