Scientists find another reason sex is good for you!

And this one is a big one --- it reduces anxiety.

While examining the part of the brain that "sees" danger scientists at Princeton saw a suprising result.  They knew this part of the brain, the hippocampus, has been associated with anxiety, learning and memory.  With stress it shrinks in size, and (along with the amygdala) it is less able to differentiate what is dangerous and what causes us to be anxious.

Having sex changed all that for these test subject (rats, in this case, but the human brain acts in enough similar ways).

The hippocampus grew in the group that had sex, branching out into more complicated patterns. 

Why do we want the hippocampus to grow? 

Because the more of it that there is, the better it is at determining if something outside us is really a threat or not.  It helps to add more data points to the environment.  A bigger, more complex, hippocampus is a less anxious.

It is known that in trauma victims the hippocampus shrinks causing them to suffer from more anxiety and have a larger startle response.

Sex was found to protect the brain from the detrimental effects of stress.

What kind of sex was necessary to grow the brain?

Sex was defined as "with a partner, intercourse". 

Find Vibrators to Use with a Partner

Benedetta Leuner, Erica Glasper, Elizabeth Gould

Sexual Experience Promotes Adult Neurogenesis in the Hippocampus Despite an Initial Elevation in Stress Hormones.

PLoSOne 5 (7) 2010