Although parasomnias can take several forms, an individual is typically diagnosed with a NREM sleep arousal disorder when he or she experiences one of the following on a regular basis:
- Sleepwalking, in which the individual rises from bed and moves around while still asleep. Individuals who are sleepwalking typically cannot communicate and are awakened only with significant difficulty.
- Night terrors, in which the individual awakes abruptly from sleep in a panicked, intensely fearful state.
Individuals who experience sleepwalking or night terrors remember little or nothing of these episodes, including any dreams that may have occurred.
Occasional parasomnias are fairly common, occurring in approximately 30% of adults at some point in their lives. Therefore, NREM sleep arousal disorders are diagnosed only when the parasomnias occur repeatedly and cause clinically significant distress or impairment.