Oxygen consumption and body temperature during sleep in cold environments

Abstract

Six young soldiers slept at the following ambient temperatures: 25.5° to 26℃ (78–80℉), 15° to 18.5°C (60°–65℉) and -32° to -34.5℃ (-25°--30℉). Rectal (T_r) and skin temperatures were recorded and mean weighted skin temperature (T_s) was calculated at -hour intervals every night; oxygen consumption (Vo₂) was measured at 6-minute intervals on occasional nights. During sleep at a ‘comfortable’ temperature (25.5℃) T_r, T_s and Vo₂ decreased below the resting levels measured just before retiring. During sleep in cold environments, T_r and Ts dropped to still lower levels with the lowest values recorded at an early hour of the night. Vo₂ during sleep in the cold did not differ from values recorded during sleep at 25.5℃. Lowest values measured during sleep in the coldest environment were 35.5°C, 30.5℃ and 78 Cal/m² for T_r, T_s and body heat debt, respectively. These values may represent the limits of body cooling compatible with substantially continuous sleep in the cold. Submitted on February 19, 1959