Search

The purpose of this study was to determine the effect of 12 degrees C cold exposure for 180-minutes on the hormonal responses of sleep-deprived individuals.Participants underwent 2 cold-air trials: 1 after a normal night of sleep (ie, 6-8 hours) and 1 after 33 hours of sleep deprivation (SDEP). A venous blood sample was taken at baseline and then at 90-and 180-minute cold-exposure time points. Repeated-measures analysis of variance was used to determine significance between a normal night of sleep and SDEP for norepinephrine, epinephrine, cortisol, insulin, thyroid hormones triiodothyronine and thyroxine, glucose, and non-esterifled fatty acids.There was no significant main effect for time, trial, or interaction for insulin, thyroid hormones, epinephrine, cortisol, and glucose (Por = .05). A significant main effect for time for norepinephrine and non-esterified fatty acids was demonstrated (P.001).The lack of significant differences in the hormonal and metabolic responses to cold exposure combined with SDEP may have been because of an ability of the individual to continue to respond despite the environmental stressor or the physiological effect elicited from cold exposure, thereby possibly masking physiological responses of SDEP.On the basis of these data, SDEP combined with protracted cold exposure apparently was not a great enough stressor to cause a differential response in the hormonal and metabolic parameters.

The article entitled “Changes in Body Temperature and Basal Metabolic Rate of the Ama” (ie, Koreanpearl diving women) focuses on the thermal and metabolic responses of the remarkable Korean pearl divers(ama) who repeatedly dove into the waters of Pusan, Korea. This classic article demonstrates that the amawomen exhibited a type of acclimation termed “metabolic adaptation,” which may occur in individuals whobecome acclimatized to cold. The oral temperatures and metabolic rates of the Korean diving womendescribed in this article were measured during 4 seasons and compared with their Korean nondivingcounterparts who lived in the same community and consumed the same diet.The oral temperature of Korean diving women was measured before and after they dove for pearls in thewaters off the Pusan coast. Resting metabolic rate was also measured under the same conditions. In thesummer, the average oral temperature of the women declined to 35°C after 70 minutes of diving into 27°Cwater. In the winter months, the water temperature averaged 10°C, permitting the women to dive for only 15minutes. During this time, their oral temperatures declined to 33°C. Because the oral temperature declinedwith respect to the water temperature conditions, the duration of the work for the women was primarilydetermined by the water temperature and their ability to endure the extreme cold. The basal metabolic rateof the ama pearl divers varied with the season, implying that in the winter months the elevated (basal)