Circadian rhythm of electrical activity and motility of the stomach in cats and their relation to sleep--wakefulness stages.

Polysomnographic recordings were done over continuous 3 days together with those of electrical and mechanical activities of the stomach using chronically implanted electrodes and force-transducer in unanesthetized and unrestrained state of 4 adult cats. Circadian rhythm of the basic electric rhythm (BER) and mechanical activity in the stomach accustomed to feeding schedule of once a day was divided into the two; the fed state from the end of feeding to 8 to 11 hr later and the succeeding fasting state. However, differentiation of the fasting state into the contractile and noncontractile periods, which is known in dogs, was not evident in cats. The mean BER interval was longer and the standard deviation was smaller in the fed state than in the fasting state. Among stages of wakefulness (W), drowsiness (D), light slow wave sleep (LS), deep slow wave sleep (DS) and REM sleep, the mean BER intervals in every total time during the fed state were compared with one another. A definite unidirectional finding obtained in all 4 cats was only that the mean BER intervals in the stage D were longer significantly than those in the stage W.