Nocturnal penile tumescence in healthy aging men.

This study investigated nocturnal penile tumescence (NPT) and verified degree of sleep erections by direct observation in 40 healthy, sexually nondysfunctional men aged 23-73. They were assessed under similar conditions during three nights, with systematic awakenings during tumescent episodes on the third night. Total sleep time and the ratio of total sleep time to time in bed (sleep efficiency) decreased significantly with age. Duration of REM sleep after adjustment for differences in sleep time did not vary significantly after age 30. Frequency and duration of NPT, but not degree of circumferential increases during tumescent episodes, decreased progressively with age independent of variations in sleep. In contrast to men in the younger age groups, the majority of men above age 60 did not have full sleep erections even though they and their partners reported regular intercourse. The significance of this finding is discussed in relation to the neurophysiology of erection and to NPT as a diagnostic test of impotence in aging men.