As absorbentishe said endorphines a natural "upper" chemical is released in the brain.
There are so many more benefits to having an orgasm that it seems to me like it might be unhealthy to go without one. I have also read that a man who masterbates more often (within reason) can help to prevent prostate cancer.
"Affectionate touch increases levels of oxytocin, a desire-enhancing chemical secreted by the pituitary gland which she labels the "bonding hormone."
"Regular lovemaking can increase a woman's estrogen level, protect her heart, and keep her vaginal tissues more supple"
A bout of bedtime activity can raise the amount of
oxygen in cells, keeping organs and tissues functioning at their
best.
DHEA (dehydroepiandrosterone), the latest health-fad hormone on the market, is released naturally during amorous athletics. "Just before orgasm and ejaculation," DHEA is believed to improve brain function, balance the immune system, help maintain and repair tissue, promote healthy skin, and possibly improve cardiovascular health and combat depression.
http://www.bojiggly.com/articles/hea...of-orgasm.html