Synchronized sleep duration is related to tonic vasoconstriction of thermoregulatory heat exchangers

The relationship between duration of the ultradian sleep cycle and intensity of tonic vasoconstrictor sympathetic outflow to thermoregulatory heat exchangers was studied in cats chronically implanted with EEG and EMG electrodes, and temperature transducers. Vasoconstrictor sympathetic outflow to heat exchangers was indirectly appraised by measuring the difference between hypothalamic temperature and ear pinna temperature. The vasoconstrictor sympathetic outflow was varied experimentally by means of thermal and vascular manipulations. The results show that the duration of the stage of synchronized sleep, but not that of the stage of desynchronized sleep of the ultradian sleep cycle, is correlated positively with the intensity of tonic vasoconstrictor sympathetic outflow to heat exchangers in the thermal zone of vasomotor regulation of body temperature.