Preferred ambient temperature for old and young men in summer and winter

To investigate the effects of age on thermal sensitivity, preferred ambient temperature (T_pref) was compared between old (71–76 years) and young (21–30 years) groups, each consisting of six male subjects in summer and winter. The air temperature (T_a) was set at either 20° C or 40° C at commencement. The subject was directed to adjust theT_a for 45 min by manipulating a remote control switch to the level at which he felt most comfortable. In the older group, theT_pref was significantly lower in trials starting at 20° C than that starting at 40° C in summer. The fluctuation ofT_pref (temperature difference between maximum and minimumT_a during the last 10 min) was significantly wider in the older group in both summer and winter. Repetition of the same experiment on each subject showed a poorer reproducibility ofT_pref in the older group than in the younger group in summer. Tympanic and esophageal temperatures of the older group kept falling throughout the trial starting at 20° C in summer. These results suggest that thermal sensitivity is decreased with advancing age and that thermal perception in the elderly, especially to cold, is less sensitive in summer.