Influence of Long-Term Exposure to an Air-conditioned Environment on the Diurnal Cortisol Rhythm

In the present study, the influence of the long-term use of air-conditioning in summer on the cortisol rhythm was examined by measuring the rhythm in subjects who had been exposed to air-conditioning for a short [S] or long [L] time. Investigations were conducted twice in July and September. Atmospheric temperature and relative humidity near the subjects were measured for three days in each season. Saliva samples for cortisol analysis were collected every 2 hours during the daytime beginning at 8:00 h with subsequent sampling times at 10:00, 12:00, 14:00, 16:00, 18:00, 20:00 and 22:00 h. A questionnaire on sleep and duration of air-conditioning use was also undertaken. Ambient mean temperature was higher in the S group (mean±SD; 30.8±1.2°C in July, 28.0±0.8°C in September) than in the L group (28.0±1.2°C in July, 27.3±1.0°C in September) (p