53 Hrs Of Sleep Deprivation On Thermoregulation During Multiple Stages Of Acute Cold Exposure

Abstract

BACKGROUND: While the effects of sleep deprivation have proven to be psychologically detrimental, the physiological responses remain unclear. Sleep deprivation may alter a number of physiological processes; thereby suggesting that in combination with cold exposure, the ability of the body to maintain thermoregulatory homeostasis may be impaired. The relationship between sleep deprivation and thermoregulation has not been extensively evaluated. PURPOSE: To evaluate the effect of 53-hrs of sleep deprivation on the thermoregulatory responses of young adult Caucasian males during multiple bouts of acute cold exposure. METHODS: Eight males (22.8 ± 1.7 y) underwent two conditions [control (CON) or sleep deprivation (SDEP)] during which they were exposed to cold air (10°C) for 120-min, once per day, for 3 consecutive days (i.e., stage 1, 2, 3) beginning at 6:00am. Rectal temperature (Tre), mean skin temperature (Tsk) and oxygen consumption (VO2) was collected at baseline (BASE) and 5-min, 15-min and every 15-min thereafter for the duration of the trial. Additionally, physical activity (PA) was continuously monitored with the use of an accelerometer. RESULTS: Condition (SDEP, CON) by time (BASE, 5, 15min and every 15min until 120min), repeated measures ANOVAs revealed a significant interaction for Tre, (p = 0.02) during stage 2. The interaction was due to a significantly greater Tre (p < 0.05) in the SDEP vs. the CON condition during BASE and minute 5 and 15 of ACE and no difference thereafter during Stage 2 of ACE. As expected, during SDEP volunteers expended 400 ± SD more kcals than CON as a result of increased (p = 0.001) PA (SEDP 679,470.00 ± 135,598.89 counts, CON 389,024.13 ± 114,933.04 counts). Multilevel model regression analyses then demonstrated that daily PA across both conditions was positively associated (p≤0.01) with BASE Tre across the final 2 stages. CONCLUSION: SDEP appears to affect an individual's thermoregulatory response in a cold environment as the sleep deprived volunteers exhibited a greater Tre in SDEP than CON.