Rapid Eye Movement (REM) Sleep

Humans go through several stages of sleep during a typical night. One of them is the period during which we have complex dreams, called rapid eye movement (REM) sleep. During REM sleep our eyes move about rapidly beneath closed eyelids, even though our bodies typically remain completely motionless.

The explanation for rapid eye movement during REM sleep has always remained somewhat of a mystery - until now. In the June issue of Brain, researchers report that the most likely explanation is that our eyes are trying to follow the action in our dreams. They came to this conclusion after studying the direction of eye movements in a group of subjects who have a particular sleep disorder in which they physically act out their dreams while sleeping. The patients’ eye movements tracked their physical actions with a consistency of nearly 90%. The eye movements in these patients were no different than in normal subjects who did not move physically during sleep, leading the authors to suggest that the “follow-the-dream-action” explanation for REM activity may hold for normal subjects as well.