Sweating it out: The influence of sex and emotions on human sweat production

Human sweat conveys a wealth of information about its donors, including their emotional state at the time of release. While extensive research has examined the communicative potential of human sweat, the mechanisms underlying emotional sweat production remain underexplored. This study employed a data-driven approach with a large sample of sweat donors (N = 334; most participants were university students) to investigate the relation between sweat production and the emotional state of males and females across three conditions - fear, happiness, and rest. Four key questions were addressed: (i) Do males produce more sweat than females across emotional conditions? (ii) Does sweat production vary as a function of emotional experience? (iii) Is sweat production associated with self-ratings of emotional experience? and (iv) Are there sex differences in these associations? Results revealed that males produced significantly more sweat than females in fear-inducing conditions, which also showed the highest overall sweat production. Contrary to prior findings, happiness-related sweat production did not exceed that of rest in either sex, a discrepancy potentially due to contextual factors. Moreover, sweat production was positively associated with reported negative emotional experience during the fear-inducing sessions, but only for males. This suggests that male, but not female, donors may have the capacity to encode emotional intensity in sweat production. These findings provide new insights into the physiological and contextual factors that shape emotional communication through sweat, with potentially important implications for future research. Additionally, the observed sex asymmetries are discussed in light of a possible evolutionary explanation.