A sleep determination apparatus capable of detecting wakefulness of a subject before entering a hypnagogic state with high accuracy is provided. When the subject is not yet in the hypnagogic state, it is determined that the subject is asleep when a detected body movement signal continuously remains below a determination threshold for a predetermined time or longer, and that the subject is awake in other situations. When the subject has entered the hypnagogic state, it is determined that the subject is awake when the detected body movement signal continuously remains above the determination threshold for the predetermined time or longer, and that the subject is asleep in other situations.
Sleep determination apparatus