Sex differences in pain and thermal sensitivity: the role of body size.

Sex differences in heat-pain and thermal sensitivity were investigated in 32 women (20 to 60 years of age) and 32 men (17 to 63 years of age) who had no somatosensory impairments. Pain thresholds were measured with stimuli of two different durations (phasic and tonic). Warmth and cold thresholds were assessed as indices of thermal sensitivity. Stimulation was applied to the hand and to the foot by an apparatus containing a Peltier thermode. There were no sex differences in heat-pain thresholds. Women had significantly lower warmth thresholds than men (more pronounced on the foot than on the hand), but similar cold thresholds. Measures of body size (weight, height) correlated much more strongly with thermal than with pain sensitivity, and helped to explain the sex difference in the warmth threshold. A reduction of sex differences to body-measure differences appears likely, but could not be demonstrated unequivocally.