Circadian rhythms of core body temperature and urinary noradrenaline secretion under the influence of skin pressure due to foundation garments worn during wakefulness

The present experiment investigated the effects of skin pressure by foundat ion garments (brassiere plus girdle) worn during wakefulness on the circadi an rhythms of core temperature and endocrine secretion. Eight healthy femal es (18-23 yrs) maintaining regular sleep-wake cycles for a week prior to pa rticipation in the experiment served as participants. The experiments were performed from June to August, 1999, using a bioclimatic chamber controlled at 26.5 +/- 0.2 degreesC and 62 +/- 3% RH. Ambient light intensity was con trolled at 5001x from 07:30h to 17:30h, 1001x from 17:30h to 19:30h, 201x f rom 19:30h to 23:30h and there was total darkness from 23:30h to 07:30h. Th e experiment lasted for 58h over 3 nights. The participant rose at 07:30h i n the morning of the first day and retired at 23:30h, adhering to a set sch edule for 24 h but without wearing foundation garments. From 07:30 h to 23: 30 h of the second day the participant wore foundation garments but did not wear foundation garments during the sleep. Rectal and leg skin temperature s were continuously measured throughout the experiment. Urine was collected every 4h for the analysis of catecholamines. Skin pressure applied by the foundation garments was in the range 11-17 gf/cm(2) at the regions of abdom en, hip, chest and back. The main results were as follows: Rectal temperatu re was significantly higher (p < 0.01) during wakefulness, but significantl y lower (p < 0.01) during sleep with than without foundation garments. Furt hermore, the amplitude of rectal temperature was larger with than without f oundation garments (p < 0.033). Urinary noradrenaline was mostly lower with foundation garments throughout the day and night. The results suggest that skin pressure by foundation garments worn during wakefulness could influen ce the level of core body temperature and noradrenaline secretion not only during wakefulness, but also during sleep.