抄録
A method and results of the analysis of the regularity in the distribution of REM episodes across nights are presented. REM episodes in the sleep of consecutive nights were measured using automatic sleep staging system reported in our previous paper. In these measurements, subjects spent every day in normal conditions at the longest for 21 days.
Five types of models of REM-NREM sleep distributions have been tested; (1) a clock time dependent model, (2) a consistent phase shift model across nights, (3) a sinusoidal phase changing model, (4) a sleep-onset dependent model, (5) a model of no systematic phase shift.
We have obtained the best fit of data to the model (3). Timing of REM episodes shifts almost sinusoidally with a half or an hour amplitude and 14-15 day period. This sinusoidal shift implies the relative coordination due to the entrainment of REM rhythm by 24 hours L-D cycle. The difference of amplitude among subjects is considered due to that of the strength of the entrainment. Thus the analytical method reported here will contribute to the quantitative study of properties of human sleep especially of REM-NREM cycle.
