To determine whether or not someone suffers from like a sleep-arousal disorder A.K.A. parasomina, researchers will videotape the person sleeping in attempt to record a mid-slumber episode. They will also use polysomnographs. They're used to monitor several bodily functions, including eye movements, breathing, and brain-wave patterns. It is thought that homicidal somnambulism (killing someone while you sleep) is related to night terrors and both usually occur two hours nodded off during deep, slow wave sleep.
