53 Hrs Of Sleep Deprivation On Catecholamine Responses During Multiple Stages Of Acute Cold Exposure: 2475: Board #83 June 4 8:00 AM - 9:30 AM

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BACKGROUND: Increases in sympathetic nervous system stimulation are associated with alterations in hormonal responses. While research has demonstrated that circulating epinephrine (EPI) and norepinephrine (NE) levels are increased in response to acute cold exposure in an attempt to maintain core body temperature (Tcore), the hormonal responses to sleep deprivation remain poorly understood. Exposure to a cold environment in conjunction with sleep deprivation may alter hormonal release and regulation; thereby altering physiological functions i.e., maintenance of Tcore.

PURPOSE: To evaluate the effects of 53-hrs of sleep deprivation on the catecholamine responses of apparently healthy Caucasian males during multiple bouts of acute cold exposure.

METHODS: Eight apparently healthy, young (22.8 ± 1.7 y), Caucasian males participated in two experimental trials [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 (Stages 1, 2, and 3). Venous blood samples were taken at baseline (0-min) and 120-min during Stages 1 and 3 of ACE.

RESULTS: The mixed regression model was utilized to examine changes in EPI and NE across time, as well as to determine the potential of EPI and NE concentrations to predict Tcore responses during ACE for both conditions (SDEP, CON). There were no significant increases in EPI or NE across time. Furthermore, the random effects model revealed that neither EPI (p=0.210) nor NE (p=0.521) significantly predicted Tcore.

CONCLUSION: While EPI and NE concentrations were slightly altered during cold exposure for both conditions, the contribution of each stressor on the catecholamine responses is uncertain. Furthermore, the ability of EPI and NE concentrations to predict Tcore remains unclear and warrants further investigation.