Electrophysiological semeiology of sleep.

The main characteristics of electroencephalograms, electro-oculograms and electromyograms in human sleep are described. This electrophysiological semeiology permits the identification of the different stages in normal sleep. In animals, sleep is generally less differentiated; the possibility of recording subcortical structures allows the observation of additional phenomena such as hippocampal theta activity and PGO spikes. Evoked brain electrical activity is less well known than the spontaneous activity in sleep. Recent technological developments offer many interesting possibilities in the processing of the EEG and other physiological signals.