Motion sickness, nausea and thermoregulation: The “toxic” hypothesis

Abstract

Principal symptoms of motion sickness in humans include facial pallor, nausea and vomiting, and sweating. It is less known that motion sickness also affects thermoregulation, and the purpose of this review is to present and discuss existing data related to this subject. Hypothermia during seasickness was firstly noted nearly 150 years ago, but detailed studies of this phenomenon were conducted only during the last 2 decades. Motion sickness-induced hypothermia is philogenetically quite broadly expressed as besides humans, it has been reported in rats, musk shrews and mice. Evidence from human and animal experiments indicates that the physiological mechanisms responsible for the motion sickness-induced hypothermia include cutaneous vasodilation and sweating (leading to an increase of heat loss) and reduced thermogenesis. Together, these results suggest that motion sickness triggers highly coordinated physiological response aiming to reduce body temperature. Finally, we describe potential adaptive role of this response, and describe the benefits of using it as an objective measure of motion sickness-induced nausea.

Cybersickness provoked by head-mounted display affects cutaneous vascular tone, heart rate and reaction time

“…This finding is of major interest as it is in line with our recently presented concept that disturbances in thermoregulation are a key element of nausea in general and of motion sickness-related nausea in particular [28]. Furthermore, the finding is in full accord with previous reports of reduction of coldinduced finger vasoconstriction in nauseated humans [30,31].…”

“…Selection of physiological variables in these and other works were based on empirical evidence provided by numerous earlier works with motion provocation. There is however a growing body of evidence suggesting that disturbances in temperature is a key element in the pathogenesis of motion sickness (see [28] for review), and thus it would be more productive to focus on relevant thermoregulatory indices. It appears that motion sickness triggers coordinated physiological response directed towards reducing body temperature -increase in heat loss via sweating [9,12,15,17,18,26,31,44], reduced thermogenesis [30], altered perception of ambient temperature and preference for cooler environment [32].…”

Autonomic changes induced by provocative motion in rats bred for high (HAB) and low (LAB) anxiety-related behavior: Paradoxical responses in LAB animals

“…However, contrary to our expectations, the LAB rats had the largest magnitude of hypothermic and cardiovascular responses to motion. The basis for this unexpected response and the implications for the "hypothermia nausea hypothesis" [33] are discussed below.…”

“…4 mechanism [33], with an observed fall in body temperature, which occurs, at least in part, due to regionally specific cutaneous vasodilatation that favors heat loss [35].…”

“…It is well documented, but not widely known, that in humans nausea is commonly associated with a fall in the core body temperature that is caused, at least in part, by local vasodilation at specific cutaneous sites (reviewed by [33]); this phenomenon is proposed to represent an evolutionary beneficial adaptive response to protect body metabolism during presence of a toxin [33]. We have recently demonstrated that similar hypothermic responses are present in rats (lacking an emetic reflex [19]) and in house musk shrews (Suncus murinus, an insectivore possessing emetic reflex) [9,35].…”