It can be sometimes be difficult to distinguish the sleepwalking state from wakefulness. Although this girl is clearly pretending, she does sleepwalk on a regular basis (as the author can confirm because she is his daughter).

From ghoulies and ghosties,
 And three leggity beasties,
 And things that go bump in the night,
 Good Lord, deliver us.
 Old Scottish Prayer

The traditional view that parasomnias reflect the unwelcome intrusion of some nocturnal spirit or supernatural force into sleeping people has largely been superseded. However, sleep-related behavioural phenomena are still a common cause of considerable anguish and perplexity to the sufferers, their bed partners, and clinicians alike. A common misperception among the last is that detailed and expensive investigations are invariably needed for precise diagnosis. However, I hope this article will demonstrate that a working knowledge of parasomnias and the spectrum of their presentation will allow a confident diagnosis and treatment, if needed, in most cases from the history alone. In complex situations, especially if there is no witness or bed partner, the input from a sleep clinic experienced in managing parasomnias is undoubtedly helpful. But in practice, it is relatively rare for overnight polysomnography complete with full EEG recording, video monitoring, and multiple limb EMG channels to provide additional worthwhile diagnostic information.

Parasomnias have a considerable range of type and severity. Most classifications are based on the stage of sleep from which the events are most likely to occur (table 1). Overall, the non-rapid eye movement (REM) parasomnias are more common although REM parasomnias are more likely to be seen in general neurological practice.

With notable exceptions (such as REM sleep behaviour disorder), it is rarely appropriate to treat parasomnias with medication, certainly not for prolonged periods. In fact the evidence base for effective drug therapy is …