Sleep parasomnias refer to disorders of arousal, partial arousal or sleep-wake transition.

Parasomnias are divided into 3 main classes.

• Disorders of arousal (from NREM sleep)
  • Confusional arousals
  • Sleep terrors
  • Sleepwalking
• Parasomnias usually associated with REM sleep
  • Nightmare disorder
  • REM sleep behavior disorder
  • Recurrent isolated sleep paralysis
• Other parasomnias
  • Sleep related dissociative disorders
  • Sleep enuresis
  • Sleep related groaning (Catathrenia)
  • Exploding head syndrome
  • Sleep related hallucinations
  • Sleep related eating disorder
• Parasomnia, Unspecified
• Parasomnia due to drug or substance
• Parasomnia due to medical condition

The NREM parasomnias typically occur during slow wave sleep (stage 3) but can occur from stage 2 sleep and is due to an incomplete arousal from sleep. It is associated with apparent arousal, mental confusion, (Confusional arousals) to agitation, screaming and autonomic involvement, (Sleep terrors) to getting up and either walking around or performing tasks while still asleep (Sleep walking). They usually occur in the first half of the night but can occur later in the night. Usually occur no more than once a night but have been described in some cases to occur multiple times a night. In patients with teenage onset of sleepwalking, epilepsy and nocturnal seizures should be considered as differentials. The typical age for presentation of night terrors is 4-12 years of age, while confusional arousals present at an earlier age. Also, parasomnias appear to be familial. Most events last between 3-5 minutes and self terminate. Typical of any of the events is a lack of recollection on the part of the offending individual.