Evoked potentials during REM sleep reflect dreaming.

Polygraphic recordings were collected for 11 normal subjects during sleep and wakefulness in order to investigate characteristics of the rapid eye movement (REM) associated potentials. EEGs were averaged using 5 different triggering points: (1) saccade onset under the normal ambient illumination, (2) saccade onset in the total darkness, (3) onset of REMs during REM sleep, (4) flash during REM sleep, and (5) flash during stage 2 sleep. In the central area, positive potentials appeared with waking saccades under the normal ambient illumination (P240L) and REMs (P185R). The latency of P185R associated with REMs was significantly shorter than that of P240L associated with waking saccades. These findings suggest that P185R is evoked by PGO waves occurring just before the REM. A small positive potential appeared in the occipital area with waking saccade under the normal ambient illumination (P260L) and REMs in the total darkness (P250R). Conspicuous absence of these waves for waking saccades in the total darkness suggests that P250R accompanied with REMs reflects activities involved with the cognitive processes occurring when a subject scans a dream image during REM sleep.