PERIPHERAL THERMAL RESPONSIVITY TO FACIAL COOLING DURING SLEEP

A recently developed technique for examining thermal sensitivity durin g sleep was used to assess whether skin and core temperature responses to thermal stimulation were altered by sleep state. The technique was designed to probe thermal responsivity without altering core body tem perature or inducing awakening. Twenty-seven young men and women were studied during a sleep deprivation night and a sleep night three night s later. Cold water stimulation of the face alternated with an equal p eriod of rewarming across a 40-min cycle throughout the night. Skin te mperature from the finger and rectal temperature were continuously ass essed. Sleep continuity and architecture were largely uninfluenced by the thermal stimulation. Finger skin temperature decreased during cold facial stimulation in both sleep and waking states. Skin temperature changes during sleep were approximately one-fifth the magnitude of tho se during waking. Core temperature was minimally influenced. REM sleep was associated with a greater amplitude decrease in finger temperatur e than was non-REM (NREM) sleep. The results support the utility of th e technique as a probe of thermal responsivity during sleep and sugges t a reduction of thermal responsivity during sleep and, more tentative ly, an altered responsivity during REM versus NREM sleep.