While we’d like to think that this post-coital love surge is simply how we feel, the truth is it may have more to do with the orgasm-induced rush of oxytocin.

Why is this happening?

Susan Kuchinskas, who writes a blog about oxytocin and has a book, Love Chemistry: How Oxytocin Lets us Trust, Love and Mate, due early in 2008, offers some insight:

“Oxytocin seems to have been ‘designed’ by nature to make a man and woman feel bonded after sex, so they would stay together and raise children,” she says. “Today, the physiology of men and women still plays out according to this pattern. But estrogen seems to increase the calming and bonding effects of oxytocin, while testosterone seems to mute them. That's why women tend to feel more attached after sex than men do.”

The website oxytocin.org sites a study that found oxytocin can also be released in response to intense emotions. In the study, women were asked to recall positive and negative relationship memories.