Somnambulism

Jacques-Louis David, "Mars Disarmed by Venus" (1824)

… Sleepwalkers are suggestible, and are therefore quite likely to engage in activities they have heard about or perhaps watched earlier that day. This can, at times, include embarrassing behaviour lapses, such as attempts to relieve themselves in public, chewing on non-existent food, dusting or sweeping without a duster or other cleaning implement – even engaging in inappropriate sexual intercourse.

There is a tendency not to remember anything which has happened during bouts of sleepwalking, so onlookers need not fear subsequent embarrassment from any encounter or conversation. They should, however, confine themselves to short questions or statements when dealing with somnambulists, as any requests for longer or more complex information will probably be greeted with silence or inaction.

It is a fallacy to believe that sleepwalkers are incapable of committing crimes or indiscretions – people have even committed murder in their sleep. However, acts such as these are fortunately very rare.

– Home Encyclopedia of Psychology, ed. Greg O’Bannon (London: Macmillan, 1986), p. 448.