A recent paper in Dec 2009 found no greater mental health problems among students who "hook up" than students who don't.
I thought of this paper while reading the sex chapter in a book by psychiatrist Frederic Flach (1927-2006) who wrote much on resilience and depression. The thing I find so refreshing about his writing is how theory-based it is. I do not know whether the theories are right, but they allow him to tell a cohesive story in a way that data-driven writing would not.
1. Adolescence is a time for identity formation. Early sex interferes with that purpose of adolescence, and prevents sex from being integrated with their full identity. Sexual pressure may translate into substance use instead of the sex that they're not prepared for.
2. It's good that sexual guilt has been removed, but guilt also had a good effect of keeping people out of sexual affairs that may hurt people's self-worth or sense of personal integrity and lead to depression, such as marital infidelity, premature sex, or degrading situations.
3. The modern era has depersonalized many aspects of life, and people may be treated as statistical objects instead of people. Alienation is not rare. Sex has also been made impersonal in some contexts, but that may be because of the general social phenomenon of depersonalization, rather than something unique to devaluing sex (as some claim).
4. Sex may also be used to alleviate general loneliness and alienation, rather than for sexual purposes, and it's not successful at that. Low self-esteem in fact makes it hard to create a good relationship with trust and love, thus further reducing self-esteem.
5. Based on theories of Erikson and Buber, it's important for sex to occur within a framework of emotional intimacy, love, trust, and sharing everyday activities and life. If the primary sexual outlet is casual sex, "the inevitable enhancement of self-esteem that results from the complete experience does not occur and a slow, progressive waning in self-worth takes place, however it may be denied. Sexual harmony is not rooted in fine technique; rather, its foundation lies in both partners generously sharing with each other their bodies and their souls." (p. 97-98).
What I like the most about this analysis is that it posits distinct theories about what will happen in dynamic way that we can't capture easily with quantitative data. Data has to be extensive in order to capture a primary sexual outlet being casual sex, the absence of love, and a decline in self-worth. Not to mention being able to define and measure love and self-worth in meaningful ways. And the existing quantitative data on casual sex doesn't come close to being able to capture this.
This analysis does imply that given the choice of sex without love or no sex at all, the latter is preferable. Alternatively, it's optimistic, rejecting the idea of love as ever impossible.