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Seasonal acclimatization is known to result in adaptations that can improve heat tolerance. Staff who operate on burn injuries are exposed to thermally stressful conditions and seasonal acclimatization may improve their thermoeffector responses during surgery. Therefore, the aim of this study was to assess the physiological and perceptual responses of staff who operate on burn injuries during summer and winter, to determine whether they become acclimatized to the heated operating theater. Eight staff members had physiological and perceptual responses compared during burn surgeries conducted in thermoneutral (CON: 24.1 ± 1.2°C, 45 ± 7% relative humidity [RH]) and heated (HOT: 31.3 ± 1.6°C, 44 ± 7% RH) operating theaters, in summer and winter. Physiological parameters that were assessed included core temperature, heart rate, total sweat loss, sweat rate, and urinary specific gravity. Perceptual responses included ratings of thermal sensation and comfort. In summer, CON compared to winter CON, baseline (85 ± 15 bpm VS 94 ± 18 bpm), mean (84 ± 16 bpm VS 93 ± 18 bpm), and peak HR (94 ± 17 bpm VS 105 ± 19 bpm) were lower (p < 0.05), whereas core temperature was not different between seasons in either condition (p > 0.05). In HOT, ratings of discomfort were higher in summer (15 ± 3) than winter (13 ± 3; p > 0.05), but ratings of thermal sensation and sweat rate were similar between seasons (p > 0.05). The surgical team in burns in Western Australia can obtain some of the physiological adaptations that result from seasonal acclimatization, but not all. That is most likely due to a lower than required amount of outdoor heat exposure in summer, to induce all physiological and perceptual adaptations. [ABSTRACT FROM AUTHOR]

This article discusses the impact of climate change on human heat stress and the limitations of using the wet-bulb temperature as an index of heat stress. The wet-bulb temperature is often used in various indices to predict human heat stress, but it underestimates the impact of climate change on human thermoregulation, especially at lower humidity. The article highlights the importance of considering factors such as air movement and boundary layers in accurately quantifying heat exchange. The authors suggest using more complex models that take into account multiple variables to better predict human responses to heat stress. [Extracted from the article]

Background: Several behaviors have been reported to interfere with sleep in otherwise healthy adults, including low physical activity (PA) levels. However, few studies have compared low PA with the other behavioral risk factors of objective sleep impairment, despite the behavior tending to cooccur in highly stressed and affectively distressed individuals. Thus, the authors compared objective and subjective measures of PA and other potential sleep disrupting behaviors as predictors of objective sleep (sleep onset latency, actual sleep time, total sleep duration, awake time, and sleep efficacy) at baseline (T1) and 3 months later (T2). Methods: A community-derived sample of 161 people aged 18–65 years were asked about PA, other behavior (ie, night eating, electronic device use, watching television, caffeine and alcohol use), stress, affective distress (ie, anxiety, depression), and demographics including shift work and parenting young children in an online questionnaire at T1 and T2. PA and sleep were also monitored for 24 hours each at T1 and T2 using actigraphy. Results: Multiple regression analyses indicated that sleep at T1 was associated with PA (ie, total number of steps, metabolic equivalents/time, time spent travelling) after controlling mean ambient temperature and relevant demographics. At T2, longer sleep onset latency was predicted by parenting young children and night time television viewing; shorter sleep duration was predicted by female gender; and awake time and sleep efficacy were predicted by alcohol intake after controlling T1 sleep measures, demographics, and mean ambient temperature. Conclusion: The risk factors for objective sleep impairment included parenting young children and watching television at night, whereas better sleep outcomes were associated with greater engagement with PA. [ABSTRACT FROM AUTHOR]