Abstract: | The aim of this study was to evaluate the thermoregulatory changes induced by 27-h of sleep deprivation (SD) in men at rest both in a comfortable ambient temperature and in cold air. A group of 12 male subjects were placed in a comfortable ambient temperature (dry bulb temperature,T
db = 25° C, relative humidity, rh = 40%–50% , clothing insulation = 1 clo) for 1 h and then they were submitted to a standard cold air test in a climatic chamber for 2h (T
db=1° C, rh = 40%–50%, wind speed = 0.8 m·s–1, nude), before and after 27 h of sleep deprivation. Thermoregulatory changes (rectal temperature,T
re; mean skin temperature,
sk; metabolic heat production
) were monitored continuously. At comfortable ambient temperature, no significant change was observed after SD forT
re,
sk and
. During the cold test,T
re did not change but
sk and
were higher after SD (P<0.05). Increased
(+ 6%,P < 0.05) was related to earlier and higher shivering, with a possible increase in the sensitivity of the thermoregulatory system as shown by the shorter time to onset of continous shivering (d): 8.66 (SEM 1.33) min versus 28.20 (SEM 1.33) min (P < 0.001) and by a higher
sk observed at d: 27.60 (SEM 1.40)° C versus 21.40 (SEM 0.60)° C (P < 0.001). These results were associated with higher cold sensations and shivering following SD. They also suggested that SD modified thermoregulatory responses at a central level especially in a cold environment. |