Non rapid eye movement (REM) sleep arousal disorder describes episodes of incomplete awakening from sleep and can involve either sleepwalking or night terrors.

Sleepwalking: rising from bed during sleep and walking about, usually occurring during the first third of the major sleep episode. While sleepwalking, the person has a blank, staring face, is relatively unresponsive to the efforts of others to communicate with him or her, and can be awakened only with great difficulty. On awakening (either from the sleepwalking episode or the next morning), the person has amnesia for the episode (i.e., doesn’t remember its occurrence).

Within several minutes after awakening from the sleepwalking episode, there is no impairment of mental activity or behavior (although there may initially be a short period of confusion or disorientation).

Sleep terrors: Recurrent episodes of abrupt physiological arousal that partially awaken the person in a state of fear, and usually beginning with a panicky scream. The intense fear during each episode is accompanied with symptoms of autonomic arousal, such as mydriasis, tachycardia, rapid breathing, and sweating. There is relative unresponsiveness to efforts of others to comfort the individual during the episodes.

The sleep disturbance causes clinically significant distress or impairment in social, occupational, or other important areas of functioning.

The disturbance is not due to the direct physiological effects of a substance (e.g., a drug of abuse, a medication) or a general medical condition.

This disorder is now termed non-REM sleep arousal disorder classified under sleep-wake disorders category in the updated 2013 DSM-5. Diagnostic code 307.46.