There was a new article on MSNBC that showed a study that examined the relationship between lowered stress levels and increased sexual activity and affection.
Here is a link to the article.
http://www.msnbc.msn.com/id/28146086 I think it is one of those "Well DUH" studies since almost everyone alive knows the stress relieving properties of a great relationship and sex life.
For me, I think the reason for this is that humans are hardwired to be social creatures, so being with someone in a relationship triggers and stimulates that part of the brain that desires to feel accepted and like they belong. Humans are also hardwired to procreate and reproduce, so we have hormones, instincts, and parts of the brain that almost constantly demand that we seek out a mate and reproduce. When those "voices" are silenced and that feeling is fulfilled, it releases chemicals and hormones and reduces stress and quiets them for a while.
Anyone else have any thoughts on this?