Men may dream of impotency because of their anxiety over this theme. Males fear they can’t perform for their partners.
Serious athletes know they should refrain from sexual intercourse on the eve of competitions and during training. On the other hand, men may nurse secretive anxieties that their performance in bed may slacken with decreased practice.
In geographical regions where children are trophies in marriages, men have high anxieties over impotency. Offspring are crucial in maintaining the bloodline. They may have high frequency of dreams containing themes on impotency.
Reference
Gregor, T. (1981). A Content Analysis of Mehinaku Dreams. Ethos 9:4. Winter 1981. The Society for Psychological Anthropology: USA.