Eye movement patterns in REM sleep

Eye movements in 6 healthy men and women were studied for recurrent patterns during REM sleep. The REM periods of noctural polysomnograms, on 2 consecutive nights, were analyzed in each subject. A discrete scale from 1 to 8 was used to record each eye position. The total number of recorded eye positions for the 2 nights of testing varied from 1314 to 3006. The distributions of eye movement were similar for males and females, for both nights of testing for each subject, among individual REM periods, and between subjects. This was in spite of marked differences in the number and length of REM period, and in the number of eye movements per minute of REM sleep. In 5 of 6 subjects there was a marked tendency for the eyes to move between the 2 opposite lateral positions. Regardless of the eye position, the opposite movement was generally most likely, with an underlying tendency to return to the most opposite of the two lateral positions. In the remaining subject the opposite movement was also favored, but in this subject eye movements were more likely to be vertical rather than horizontal. Our data suggest that eye movements in REM sleep are organized in complex recurring patterns, with marked similarities between subjects. The significance of these patterns and the significance of deviations from these patterns require further study.