David A. Messer1, Hannah R. Koch1, Jesse L. Sims1, Mitchell E. Zaplatosch1, William M. Adams, FACSM2, Jessica McNeil1. 1University of North Carolina at Greensboro, Greensboro, NC. 2United States Olympic & Paralympic Committee, Colorado Springs, CO.

BACKGROUND: Mixed findings on associations between thirst perceptions with energy intake (EI) have been reported, however, the impact of sleeping in a hot versus temperate environment on thirst perceptions and ad libitum EI following waking has yet to be fully explored. This study investigated differences in thirst perceptions following sleep in hot (HOT) versus temperate (TEMP) environments, and whether differences in thirst perceptions are associated with ad libitum EI and macronutrient intake the next morning. METHODS: Ten healthy adults (females n = 1; age, 25±4 y; height, 177.9±7.4 cm; body mass, 75.8±13.8 kg; body fat, 13.5±7.1%) participated in a randomized crossover study where they slept overnight in an environmental chamber set at 25°C, 30% RH or 30°C, 30% RH. Thirst perceptions were measured with visual analogue scales (0-100, higher scores indicate greater thirst). Breakfast consisted of food and beverage items that were self-selected by participants. Paired sample t-tests evaluated between condition differences in thirst perceptions, EI, and macronutrient intake. Delta values between conditions (Hot condition - Temperate condition) were calculated. Spearman correlations were used to assess the strength of associations between changes in fasting feelings of thirst with changes in EI and macronutrient intake. RESULTS: There were no statistically significant differences in fasting thirst perceptions upon waking, EI (TEMP: 627±330 vs. HOT: 736±81 kcal; p=0.17), carbohydrate (TEMP: 25±13 vs. HOT: 28±13 kcal; p=0.40), fat (TEMP: 76±43 vs. HOT: 87±33 kcal; p=0.31), and protein (TEMP: 24±22 vs. HOT: 30±16 kcal; p=0.22) intake between conditions. Greater thirst perceptions prior to breakfast were associated with greater carbohydrate intake during breakfast (rs (9)= 0.83, p=0.003). Delta fasting thirst perceptions were not significantly associated with delta energy, fat, and protein intakes (p>0.05). CONCLUSIONS: No differences in thirst perceptions and EI were noted between conditions, although greater thirst perceptions were associated with greater carbohydrate intake during breakfast. This initial evidence suggests that feelings of thirst may influence carbohydrate intake during a subsequent meal, although future work with an intent of manipulating feelings of thirst/hydration on EI is needed to corroborate these findings. Grant or Funding Information: This study was funded in part by Bedgear, LLC.

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