Respiratory frequency as a function of preoptic temperature during sleep.

The effects on respiratory frequency of preoptic heating during slow-and fast-wave sleep were studied in freely moving cats. During slow-wave sleep, at neutral ambient temperature, the subliminal range of preoptic temperature for thermal polypnea extends to 0.2-0.4 degrees C above control preoptic temperature. During fast-wave sleep, at neutral ambient temperature, the subliminal range of preoptic temperature for thermal polypnea increases beyond 0.9-1.0 degrees C above control preoptic temperature. Moreover, the polypneic response is weak and unstable. The results show the suspension of a precise thermoregulatory control during fast-wave sleep in a homoiothermic species.