ABSTRACT
The physiological characteristics of REM sleep differ greatly from those of NREM sleep (Figure 6). The EOG shows bursts of irregular, conjugate rapid eye movements, whereas the EMG shows profound loss of skeletal muscle tone. Skeletal muscle activity persists only in the diaphragm, extraocular muscles, and middle ear muscles. The EEG shows desynchronized, low-amplitude, mixed-frequency activity with bursts of sawtooth waves (2-Hz to 4-Hz sharply contoured or serrated waves maximal over the central regions, often preceding clusters of rapid eye movements). Superimposed on muscle atonia are short bursts of transient muscle activity. Irregular acceleration occurs in the heart rate and the respiratory rate. Penile erection or clitoral engorgement occurs, thermal regulation becomes poikilothermic, cerebral blood flow increases, and vivid, emotionally charged dreams are experienced.
