SYNCHRONIZED SLEEP DURATION IS RELATED TO TONIC VASOCONSTRICTION OF THERMOREGULATORY HEAT-EXCHANGERS

The relationship between duration of the ultradian sleep cycle and int ensity of tonic vasoconstrictor sympathetic outflow to thermoregulator y heat exchangers was studied in cats chronically implanted with EEG a nd EMG electrodes, and temperature transducers. Vasoconstrictor sympat hetic outflow to heat exchangers was indirectly appraised by measuring the difference between hypothalamic temperature and ear pinna tempera ture. The vasoconstrictor sympathetic outflow was varied experimentall y by means of thermal and vascular manipulations. The results show tha t the duration of the stage of synchronized sleep, but not that of the stage of desynchronized sleep of the ultradian sleep cycle, is correl ated positively with the intensity of tonic vasoconstrictor sympatheti c outflow to heat exchangers in the thermal zone of vasomotor regulati on of body temperature.