The Monitor on Psychology's recent review of research on the hook-up culture was at times predictable and, at times, surprising.

Hookups are defined by researchers as "brief uncommitted sexual encounters between individuals who are not romantic partners or dating each other." These encounters can include a variety of actions including sexual intercourse ("Sexual Hook-up Culture," February 2013).

Psychologists found a significant increase in the acceptance of the hook-up culture in recent years.

"In the United States, the age when people first marry and reproduce has been pushed back dramatically, while at the same time the age of puberty has dropped, resulting in an era ... when young adults are physiologically able to reproduce, but not ... ready to settle down" (Monitor).

The average age of marriage today is close to 26; the average age for reaching puberty is 12 for girls and between 9 and 10 for boys.

How prevalent are hook-ups?

"Between 60 to 80 percent of North American college students have had some sort of hook-up experience," according to researchers.

Of sexually active people between the ages of 12 to 21, 70 percent have had a hook-up (uncommitted sex) within the last year.

Among college students the greatest predictor of hook-up behavior resulting in intercourse is that one has previously experienced a hook-up. In fact, after engaging in one hook-up, students become 600 percent more likely to engage in a second hook-up during the same semester.

Frequently, sexual hook-ups are fueled by alcohol consumption.

One recent study proved alarming to many readers. Males reported consuming six drinks, on average, prior to their most recent hook-up, while females consumed four drinks. Binge drinking is considered to be five drinks for males and four drinks for females ("Psychology Today" website).

Additional studies show consuming alcohol increases the likelihood the hook-up will result in intercourse. Adding even more concern is the fact that studies show that less than 50 percent of uncommitted couples used contraceptives during their latest hook-up.

Uncommitted hook-ups gave rise to a variety of reactions. Males were much more positive after hook-ups. A smaller percentage, about 57 percent of women, "were generally glad they had done it," according to "The Monitor."

Because the likelihood of repeating hook-ups is high, many young people eventually experience regret. In one study 72 percent of young people regretted at least one uncommitted hook-up in their past. Those with the most regret developed more symptoms of depression.

In addition, "women's but not men's degree of depressive symptoms increased with the number of previous sex partners within the last year" (The Monitor).

For many readers, this review of research in the American Psychological Association's "Monitor on Psychology" proved surprising.

Should society be concerned?

Opinions vary, of course, but for those who are concerned, the research tells parents, schools and college officials we have much to do to keep our young people physically safe and mentally healthy.