Auditory and visual evoked potentials during sleep were recorded in healthy subjects. After averaging of the evoked potentials separately for the different REM episodes, the corresponding so-called amplitude-frequency-characteristic was calculated. This function describes the transfer properties of the system in the frequency domain. Regarding the visual evoked potentials, no difference between consecutive REM episodes could be proven. Under auditory stimulation, a significant difference between the first and the following REM episodes was found in the beta frequency range (12.5 to 20 Hz). This indicates different mechanisms of information processing during consecutive REM episodes.