Influence of Stimulus Level and Sleep Stage on the Early Components of the Averaged Electroencephalic Response to Clicks during All-Night Sleep

Abstract

Ongoing EEG activity was recorded from six adults from an electrode on the vertex referred to the right and left mastoids during nine nights of natural sleep. An electrode placed near the lateral canthus of each eye was used to record eye movements. The effect of stimulus level (0 to 25 dB SL in 5-dB steps) on the early components of the averaged electroencephalic response was examined with clicks presented at a rate of five per second from a loudspeaker. Each response was averaged over 512 stimuli. Responses were sorted into the stage of sleep from which they were obtained. “Light” sleep included Stages REM and 2. “Deep” sleep included Stages 3 and 4. Response latency remained stable, while amplitude generally increased as a function of increasing sensation level. Little difference in peak latency and peak-to-peak amplitude was found when comparing light vs deep sleep. Latency measures for two consecutive nights were similar, but amplitude measures from the first night were significantly larger.