Source: DGNews  |  Posted 1 year ago

By Fred Gebhart

SAN FRANCISCO -- September 18, 2010 -- Although a low level of stage 4 sleep shows good sensitivity as a marker for violent sleepwalking, it is not a specific marker, according to a study presented here at the 135th Annual Meeting of the American Neurological Association (ANA). Similarly, low levels of stage 4 sleep can be seen in nearly half of nonviolent sleepwalkers and most violent sleepwalkers.

Stage 4 sleep has long been recognised as a potential marker for violent episodes of sleepwalking. Sleepwalking is a fairly common arousal parasomnia that affects up to 4% of adults, noted Marc-Antoine Labelle, BSc, Centre d'étude du sommeil, Hôpital du Sacré-Coeur du Montréal, Montreal, Quebec, Canada, on September 15. Sleepwalking includes a spectrum of behavioural manifestations of different degrees of complexity that usually arise from incomplete awakenings, most often from slow-wave sleep. The more violent sleep-related behaviours, such as attempting to strangle a bedmate or attacking inanimate objects, has attracted growing attention because of potential medical, legal, and forensic implications.

Little is known about why some sleepwalkers experience violent episodes. Few indicators have been uncovered, although some investigators have suggested that individuals who have <2% stage 4 sleep are at higher risk for violent episodes of sleepwalking. A literature search found no follow-up studies of the original findings from 1995, which prompted the researchers to conduct their own observational study.

Participants included 95 consecutive sleepwalkers referred to the sleep clinic at Sacré-Coeur Hospital. Complete overnight polysomnographic (PSG) recordings were available for 79 patients, who completed a detailed questionnaire, including history, suspected precipitating factors, nature and frequency of somnambulistic behaviours, history of injury or violent episodes, descriptions of their most recent episode, and details of the most complex sleep mentation that occurred during sleepwalking.

Based on the responses, 7 individuals (4 men, 3 women) reported violent behaviour, defined as any intentional act that resulted in harm to others, to the sleepwalker, or to physical objects or property. All of the violent sleepwalkers reported defending themselves against perceived threats.

The violent sleepwalkers were aged 21-48 years. The corresponding age range in the nonviolent group included 54 individuals (20 men, 34 women) who were included in statistical comparisons. The violent group was predominantly male (57% vs 37% for the nonviolent sleepwalkers). The groups showed similar sleep efficiency except in stage 4. Violent sleepwalkers had significantly less stage 4 sleep (1.5% vs 4.7%, P = .008), and a significantly greater proportion of violent sleepwalkers had <2% stage 4 sleep (86% vs 46% (P = .036).

The researchers concluded that having <2% stage 4 sleep shows good sensitivity for violent sleepwalking (86%) but low specificity (54%). Additional work is needed to better understand the possible role of slow-wave sleep in behavioural parasomnias compared with other sleep disorders.

[Presentation title: Can Stage 4 Sleep Discriminate Between Violent and Non-Violent Sleepwalkers? Poster T-37]