Evoked Responses to Clicks and Electroencephalographic Stages of Sleep in Man

Abstract
The form of the average evoked response to clicks is highly correlated with the background electroencephalogram. However, the response during the emergent low-voltage "dreaming" stage is different from that seen during the low-voltage phase at the beginning of sleep. The results provide additional evidence that the emergent low-voltage stage is a neurophysiologically unique phase.