Heat tolerance after total and partial acute sleep deprivation.

Sleep deprivation (SD) is suggested to be associated with reduced thermo-regulatory functions. This study aimed to quantify the effect of partial (PSD) and total (TSD) 24 h SD using a standard heat tolerance test (HTT). Eleven participants underwent HTT after well-rested state, PSD and TSD. No significant physiological differences were found between the exposures but subjective discomfort was higher after TSD. Evening chronotypes' temperature during HTT was higher after TSD compared with PSD (p = 0.017). After TSD, evening chronotypes compared to intermediate chronotypes' temperature was higher during the first hour of the HTT (p < 0.05), suggesting that thermo-regulatory function during exercise in the heat is influenced by chronotype.