Effects of motion sickness on thermoregulatory responses in a thermoneutral air environment.

Motion sickness (MS) has been identified as a non-thermal factor that can moderate autonomic thermoregulatory responses. It has been shown that MS exaggerates core cooling during immersion in cold (15 °C) and luke-warm (28 °C) water by attenuating cold-induced vasoconstriction. The aim of the present study was to investigate whether MS affects thermal balance in a thermoneutral air environment. Eleven subjects were exposed to rotation in two conditions, control (CN) and MS. In the CN condition subjects refrained from head movements, whereas in the MS condition they performed a sequence of maximal head movements (left, right, up, down) at 15-s intervals until they were very nauseous. Sweating rate, rectal temperature (T(re)), the difference in temperature between the right forearm and tip of the second finger (T(ff)) as an index of cutaneous vasomotor tone, perceived MS, thermal comfort and temperature perception were recorded before and during rotation, and during 90-min post-rotation. During the post-rotation period, T(re) dropped and sweating rate increased in the MS but not in the CN condition. The T(ff) response suggests that MS-induced peripheral vasodilatation which, together with the sweating resulted in increased heat loss. During rotation, subjects perceived temperature to be uncomfortably high, suggesting that MS may also affect thermoregulatory behaviour. It thus appears that also in a thermoneutral air environment MS may substantially affect thermal balance.