Rapid eye movements in REM sleep--more evidence for a periodic organization.

Density scores of horizontal eye movements during 70 REM sleep periods of normal young adults and combat neurotic patients were subjected to spectral analysis. The results showed that in 58% of all REM periods, spectral peaks occurred at either 0.1 c/min or 0.05 c/min. The percentages of spectral peaks at these frequencies were equal in both groups. Since the estimated variance at these frequencies was significantly higher than the estimated variance at the adjacent frequencies and the mean variance at the rest of the spectra, it was concluded that eye movements in REM sleep tend to cluster every 10-20 min. These results and findings on the neural control of REM ocular activity suggest that REMs in sleep are generated by at least 3 generators: a burst generator, an isolated eye movement generator, and a 10-20 min periodic generator.