Increased skin wetness independently augments cool‐seeking behaviour during passive heat stress

Abstract

Skin wetness occurring secondary to the build-up of sweat on the skin provokes thermal discomfort, the precursor to engaging in cool-seeking behaviour.r Associative evidence indicates that skin wetness stimulates cool-seeking behaviour to a greater extent than increases in core and mean skin temperatures.r The independent contribution of skin wetness to cool-seeking behaviour during heat stress has never been established.r We demonstrate that skin wetness augments cool-seeking behaviour during passive heat stress independently of differential increases in skin temperature and core temperature.r We also identify that perceptions of skin wetness were not elevated despite increases in actual skin wetness.r These data support the proposition that afferent signalling from skin wetness enhances the desire to engage in cool-seeking behaviour during passive heat stress.

Mechanisms of thermal dysregulation in primary hyperhidrosis and hypohidrosis

“…The cross-over design also ensured that personal differences in heat tolerance did not confound the amount of time receiving cooling, as subjects and controls were the same participants. However, Vargas et al (2020) only performed this examination on females when they were in the first 10 days of their menstrual cycle, or in the first seven days of their hormonal birth control placebo phase. Although this was important to ensure that the body temperature increases associated with the elevation of progesterone levels did not confound thermoregulatory behaviour, this restricted inclusion criterion limits the generalizability of the study results in pre-menopausal adult women.…”

“…These two sweating disorders have been clinically acknowledged in terms of the autonomic role of sweat in evaporative cooling. However, new evidence reported by Vargas et al (2020) indicates that sweat may have a greater role in behavioural thermoregulation, which may have implications for patients with primary hyperhidrosis and primary hypohidrosis. The present study by Vargas et al (2020) tested the hypothesis that increases in skin wetness enhance cool-seeking behaviour when passive heat stress is applied.…”

“…The results of this study provide evidence for a greater role of sweat in behavioural thermoregulation. The evidence reported by Vargas et al (2020) suggests that sweat may increase cool-seeking behaviour in addition to propagating heat transfer from the skin to air. This has implications for the specialty of dermatology and the management of primary hyperhidrosis and hypohidrosis.…”

“…During the HIGH trial, the ambient humidity was raised to increase skin wetness (Vargas et al 2020). This simulates the pathophysiological conditions experienced by patients with primary hyperhidrosis, where patients have increased rates of sweat production that exceed their thermoregulatory needs (Nawrocki and Cha 2019a).…”

“…This was previously thought to occur due to the lack of evaporative cooling, resulting in decreased dissipation of body heat into the environment. The results reported by Vargas et al (2020) suggest that these adverse events may also occur due to decreased skin wetness resulting in less awareness of thermal discomfort and subsequently less cool-seeking behaviour. However, it is unclear how clinically significant this effect is, given that there are alternative mechanisms for the perception of thermal discomfort (Schlader and Vargas 2019).…”