Insomnia

Insomnia is a sleep disorder that is characterized by difficulty falling and/or staying asleep.

Hypersomnia (Daytime Sleepiness)

Hypersomnia, or excessive sleepiness, is a condition in which a person has trouble staying awake during the day.

What Are Parasomnias?

Parasomnias are disruptive sleep disorders that can occur during arousals from REM sleep or partial arousals from non-REM sleep.

REM Sleep Behavior Disorder

With REM sleep behavior disorder, the paralysis that normally occurs during REM sleep is incomplete or absent.

Circadian Rhythm Sleep Disorders

Circadian rhythm disorders are disruptions in a person's circadian rhythm -- a name given to the "internal body clock."

Non-24-Hour Sleep-Wake Disorder

Non-24-hour sleep-wake disorder is a specific kind of circadian rhythm disorder that is particularly common among blind people.

Periodic Limb Movement Disorder

Periodic limb movement disorder (PLMD) is a sleep disorder characterized by rhythmic movements of the limbs during sleep.

What Is Narcolepsy?

Narcolepsy is a neurological disorder that affects the control of sleep and wakefulness.