Non-Rapid Eye Movement Sleep Arousal Disorders
NREM sleep arousal disorders are parasomnias involving incomplete awakening from deeper non-rapid-eye-movement sleep, usually during the first third of the night.
Sleepwalking and sleep terrors
During sleepwalking, a person may leave bed and perform behaviours with a blank expression and limited responsiveness. During a sleep terror, they may sit up, scream or appear intensely frightened with rapid pulse, breathing and sweating, yet be difficult to comfort because they are not fully awake.
Little dream content and partial or complete amnesia are typical, although a fragment of recall does not rule the condition out. A single childhood episode is not necessarily a disorder; recurrence, distress, functional impact and injury risk determine the need for clinical attention.
Assessment
- Repeated incomplete awakenings arise from NREM sleep, usually early in the main sleep period, with sleepwalking or sleep terrors.
- The episodes cause significant distress, functional difficulty or meaningful risk of injury, rather than being diagnosed from unusual behaviour alone.
- Sleep deprivation, alcohol, medicines, obstructive sleep apnoea, restless legs and other causes of repeated arousal are assessed.
- REM behaviour disorder, nightmares, nocturnal seizures, panic and dissociative events may look similar and sometimes require video-polysomnography or neurological review.
Safety and treatment
Secure doors and windows, remove sharp or flammable objects, block stairs and use a low bed when falling is possible. Maintain sufficient, regular sleep and address sleep-disrupting conditions and triggers.
During an episode, guide the person calmly away from danger without confrontation or abrupt awakening unless immediate safety requires it. Frequent or dangerous episodes may benefit from scheduled awakenings or, less commonly, medication after specialist sleep assessment.
When to seek help
Request evaluation when episodes are frequent, begin for the first time in adulthood, cause injury or leaving the home, occur many times a night, or accompany snoring and breathing pauses. A safely recorded video and sleep diary can help, but no one should be put at risk to capture an episode.