Effects of skin pressure by an all-in-one undergarment on core temperature and the secretion of urinary melatonin

The present study investigated the effects of constant pressure by all-in-one, a woman's foundation garment, on the human circadian rhythms of core temperature and urinary melatonin secretion. Five healthy females participated as subjects and an all-in-one was used as the experimental garment. The subjects did not wear an all-in-one on the first day (None), but wore the experimental garments on the next four days (Wearing 1-4). Measurements made were of clothing pressure, rectal temperature and melatonin secretion. The clothing pressure on 18 body parts was measured with an air pack sensor system on the first day the all-in-one was worn (Wearing 1). Rectal temperature (Trec) was constantly measured by a thermistor probe every 10 minutes throughout the study. Overnight urine samples were collected at 07:00 on days None, Wearing 1 and Wearing 4. Our data show that the fall of nocturnal rectal temperature was significantly greater in None than Wearing and melatonin secretion was significantly higher on None than Wearing 4. In conclusion, constant skin pressure exerted by wearing an all-in-one during daytime can reduce a decrease in the rectal temperature at night and suppresses the secretion of urinary melatonin. Therefore, it could exert negative effects on sleep.