REM Behavior Disorder and Sleep
with RBD move their arms and legs in bed or talk in their sleep, or they might start sleepwalking without waking or realizing they're dreaming. The only sensations the sleeper experiences are what is occurring in their dream. And many of these dreams can be violent or frightening, causing injury to the sleeper and his bed partner.
The first series of cases of RBD was described in 1985 by Mark Mahowald, MD, and Carlos Schenck, MD, of the University of Minnesota. In Principles and Practice of Sleep Medicine (W.B. Saunders Company, 2000), they outlined several case histories of people with RBD:
"Past history and current neurological and psychiatric evaluations were unremarkable, apart from the findings reported," the authors noted. "All four men were known by day to be calm and friendly individuals."
Drs. Mahowald and Schenck and others have found that more than 90% of RBD patients are male, and that the disorder usually strikes after the age of 50, although some patients are as young as nine years old. Most RBD patients are placid and good-natured when awake; however, many of them display rhythmic movements in their legs during non-REM and slow-wave sleep.
A telephone survey of more than 4,900 individuals between the ages of 15 and 100 indicated that about two percent of those surveyed experience violent behaviors during sleep; Mahowald and Schenck estimate that one-quarter of them were probably due to RBD, which means it may be experienced by 0.5% of the population.
Studies of animals may explain REM behavior