An unpleasant, vivid dream, sometimes accompanied by a sense of suffocation. Nightmares occur during REM (rapid eye movement) sleep in the middle and later parts of the night, and they are often clearly remembered if the dreamer awakens completely. Nightmares are especially common in children aged between 8 and 10, and are particularly likely to occur when the child is unwell or anxious. In adults, nightmares may be a side effect of certain drugs, including beta-blocker drugs and benzodiazepine drugs. Repeated nightmares may be associated with traumatic experiences. Nightmares should not be confused with hypnagogic hallucinations, which occur while falling asleep, nor with night terror, which occurs in NREM (nonrapid eye movement) sleep and is not remembered the next day.


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