Even methane (natural gas) is lighter than air, but not by much. Carbon dioxide, which is contained in the air we breathe out and is also easily and safely manufactured by mixing bicarbonate of soda and vinegar, is heavier than air. It tends to sink to the floor and accumulate. So it's a good job that houses aren't air tight.
Cuddling, holding, and sexual play releases chemicals, like oxytocin, in the brain that create a sense of well-being and happiness, says Dr. Renee Horowitz, an ob-gyn who recently opened the Center for Sexual Wellness in Farmington Hills, Michigan.
Some researchers have learned that strenuous exercise releases endorphins into the blood stream. Others have found that endorphins are released during orgasm, as well as during laughter. Endorphin release may occur with frequent sex and masturbation. On the other hand, there doesn't appear to be evidence that too much sex (or exercise or laughter, for that matter) and elevated endorphin levels deplete the body of endorphins and then result in depression, etc.