Overview
Differentiate common non-REM and REM parasomnias from seizures and other nocturnal events, prioritise environmental safety, and refer new, injurious or diagnostically uncertain presentations appropriately.
Parasomnias reflect incomplete boundaries between sleep states and wakefulness. The first task is to describe timing, behaviour, responsiveness, recall and recovery rather than assume every movement is a nightmare or seizure. Witness accounts and safe home video can be especially informative because the person may have little memory. Ask how far into sleep the event occurs and whether it repeats after sleep deprivation, alcohol, stress or illness.
Non-REM disorders of arousal include confusional arousals, sleepwalking and sleep terrors. They usually emerge from deep non-REM sleep early in the night. The person may look awake but is confused, difficult to engage and poorly responsive, with limited recall next morning. Childhood episodes are common and often benign; adult onset, injury or atypical features need a broader assessment.
Nightmares are frightening dreams from which the person awakens fully and can usually recall narrative content. REM sleep behaviour disorder is different: normal muscle atonia is lost, allowing movements or vocalisations that correspond with dreams, often later in the night. New suspected RBD requires specialist confirmation and a neurological review because of its association with synuclein disorders; the conversation should explain association and uncertainty rather than imply inevitable disease.