Circadian variation of insensible perspiration in man.

Abstract

Body weight loss was measured continuously for 24 hours in lightly clothed subjects at a room temperature of 26°C and relative humidity of 60% using the bed scale (model 33B, James Addison Potter). One male, aged 38 years and four females, aged 22 years served as subjects. Skin temperatures of the chest, thigh, leg and arm were measured every ten min. and mean skin temperature was calculated. Water loss through the skin was estimated by deducting body weight loss due to respiratory gas exchange and respiratory water loss from total weight loss. Respiratory water loss was estimated by using the formula $$\dot m_e = 0.019\dot V_{0_2 } $$ (44-Pa) where $$\dot m$$ e is the rate of evaporative water loss in the expired air (g/min), $$\dot V_{0_2 } $$ the oxygen uptake (L/min STPD) and Pa is the ambient water vapor pressure. Insensible water loss through skin was found to be significantly lower between 2:00–5:00 h than in the daytime. These findings contradict the results that the value of insensible water loss was higher at night than during the day.