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.
Best example of positive feedback is the release of oxytocin during childbirth. Oxytocin is a reproductive hormone in females. Though it is also secreted in males, its function is yet unclear. Secretion of oxytocin occurs in response to nervous stimulation of the hypothalamus. It stimulates and enhances labor contractions.