Effect of reversed light-dark cycle on skin conductance in male rats

Reversal of light-dark cycle was used to investigate the effect of the circ adian changes on skin conductance, a tonic electrodermal activity parameter , in rats. Rats were adapted for 3 wk. to one of two lighting programs. The animals on the normal cycle were illuminated from 08.00-20.00; on the reve rse cycle, from 20.00-08.00. Although during Week 1 to Week 3, skin conduct ance increased gradually in both groups, this increase was more dramatic in rats adapted to light from 20.00 to 08.00 than in the other group. When th e animals on the reverse cycle were readjusted to a normal circadian cycle for 3 weeks, skin conductance decreased gradually to initial values. At Wee ks 1, 2, 3, and 6, skin conductance was significantly higher in rats on the reverse light-dark cycle than in those on the normal cycle. The present da ta suggest that changes in normal light-dark conditions affect skin conduct ance in rats.