[Temporal correlations between nocturnal spontaneous erections and sleep stages]

Early investigations on nocturnal penile tumescence (NPT) reported a close association with REM sleep; later, a less close coupling was observed under certain conditions e.g. in major depression. This supports the hypothesis that partly different mechanisms are involved in the regulation of both phenomena. In the present study, 45 male subjects suffering from erectile dysfunction were examined. Sleep was polysomnographically recorded during two consecutive nights, including registration of penile tumescence and rigidity by means of the RigiScan device. We analyzed the temporal relationship between erectile "events" and REM sleep and found that of the total of event duration, only 43% coincided with REM sleep. The majority of erections started within a range of a few minutes before or after the onset of the REM period. The data demonstrate that in patients suffering from erectile dysfunction, the coupling between NPT and REM sleep is not as close as initially presumed. This may partly reflect an abnormality characteristic for this disorder. The observations contribute to the hypothesis that the neurophysiological mechanisms governing nocturnal penile tumescence are to some degree independent from those involved in REM/NonREM sleep regulation.