Auditory evoked responses during different stages of sleep in man

Responses to auditory stimuli can be recorded from the scalp of man in all stages of sleep. At the vertex, the mean peak latency of the first positive deflection (P₁) occurs at 50 msec after stimulation; N₁, at 100 msec; P₂, at 175 msec; N₂, at 325 msec; and P₃ at 800 msec. The amplitude and latency of the components of longer latency (N₂ and P₃) increase during stages 2 through 4 sleep. The amplitude of the summed auditory evoked responses during the REM stage is considerably smaller than in the other stages and generally is of similar configuration to that of the awake state. Our results support the concept that the auditory evoked response during sleep represents summed K complexes.