Effects of daytime activity upon the timing of REM sleep periods during a night.

The effects of mental and physical daytime activities upon REM sleep cycle (REM cycle) during 1 night was studied in five university students (aged 19-25 years). Mental activity with high tension has effects upon the timing of REM sleep periods in the later part of the night. Physical activity has effects upon the timing of REM sleep in the early part of the night. The result suggests that mental and/or physical activities during daytime modulate REM cycle during the night.