Reliability of spontaneous electrodermal activity in humans as a function of sleep stages

This study was designed to examine the reliability of spontaneous electrodermal activity (EDA) as a function of the sleep stages in human subjects. Recordings were made from 10 volunteer paid male students during four complete nights. The results show that: (a) reliability of EDA varies as a function of sleep stages for both frequency and amplitude parameters although in a different way: frequency reliability shows a U-shape curve whereas amplitude reliability grows monotically with the depth of sleep and; (b) paradoxical sleep appears to be the most reliable stage for both frequency and amplitude variables. These results are compared to those obtained in waking human subjects and in sleeping cats.