What Are Parasomnias?

NREM and REM parasomnias

NREM parasomnias involve incomplete arousals from non-rapid eye movement sleep, usually deep N3 sleep. The person may appear partly awake while the brain remains partly asleep and often has little or no memory of the episode. Nightmares arise from REM sleep and are usually recalled more clearly.

Sleepwalking

A person gets out of bed and walks or performs other behaviors while not fully awake. Actions may be simple or complex, and unfamiliar surroundings or access to stairs, doors, and dangerous objects can create safety risks.

Confusional arousals

The person partially awakens but remains disoriented, responds slowly, or behaves unusually. Episodes often occur while the person is still in bed and may be followed by limited recall.

Sleep terrors

These episodes may involve a sudden cry or scream, intense fear, rapid heart rate, sweating, or attempts to escape. Despite appearing frightened, the person is usually difficult to comfort because they are not fully awake.

Sleep-related eating

A person eats or prepares food after an incomplete arousal, with reduced awareness and limited memory the next morning. Safety concerns can include consuming unsafe substances or being injured while preparing food.

Sexsomnia

Sexual behavior occurs during sleep without full awareness. Careful, respectful assessment is important because episodes may affect safety, consent, relationships, and emotional well-being.

Nightmares

Nightmares are vivid, disturbing dreams that usually occur during REM sleep and can often be recalled after awakening. Recurrent nightmares may cause distress, avoidance of sleep, and daytime impairment.

REM sleep behavior disorder

REM sleep behavior disorder involves loss of the usual muscle paralysis during REM sleep, allowing a person to move, speak, shout, or act out dreams. Episodes can cause injury to the person or a bed partner. Because the condition can be associated with neurological disorders and generally requires an overnight sleep study for diagnosis, suspected REM sleep behavior disorder should be evaluated by a sleep physician.

Why careful evaluation matters

Parasomnia-like events can have different causes. Evaluation may need to consider sleep deprivation, stress, medications, sleep apnea, seizures, REM sleep behavior disorder, and other medical or neurological conditions. Episodes that are new in adulthood, potentially dangerous, or difficult to classify warrant specialized assessment.