From Social Psychological and Personality Science:

Casual sex has become a normative experience among young people, raising concerns regarding its well-being consequences. Prior findings on main effects of casual sex on well-being are mixed, suggesting possible moderating factors. Using longitudinal and weekly diary methodologies, this study examined the moderating influence of sociosexuality, a stable personality orientation toward casual sex, on psychological well-being (self-esteem, life satisfaction, depression, and anxiety) following penetrative (oral, vaginal, or anal) casual sex among single undergraduates. As predicted, sociosexuality moderated the effect of casual sex on well-being on a weekly basis across 12 consecutive weeks, over one semester, and over one academic year. Sociosexually unrestricted students typically reported higher well-being after having casual sex compared to not having casual sex; there were no such differences among restricted individuals. Few gender differences were found. Findings are discussed in terms of authenticity in one’s sexual behaviors.

I suspect that if they did the study for older people they would find similar results. I know I find “casual sex” enhances my psychological well-being.