“People who engage in kind acts become happier over time,” says Sonja Lyubomirsky, Ph.D., a professor of psychology at the University of California, Riverside. “When you are kind to others, you feel good as a person – more moral, optimistic and positive,” says Lyubomirsky, who has studied happiness for more than 20 years. Her research, presented at the recent annual meeting of the Society for Personality and Social Psychology, found that performing kind and positive acts once a week led to the most happiness.

As for the benefit to your health, it all begins when your acts of kindness and happiness give you what is known as a “helper’s high.” This happens because, on a biochemical level, the good feelings you get when you’re happy or kind will elevate the levels of your brain’s endogenous opioids, which in turn elevate the level of dopamine throughout your bloodstream, which gives you a natural high – a helper’s high.

Then, once you have a helper’s high, your body releases a hormone known as oxytocin. In turn, oxytocin causes your body to release a chemical called nitric oxide, which dilates your blood vessels.

The ultimate effect from this chain reaction (that began with your random acts of kindness and happiness) is reduced blood pressure, which is why oxytocin is known as a “cardioprotective” hormone – it protects your heart by lowering blood pressure.

In support of this effect, a recent research study on oxytocin at the University of North Carolina at Chapel Hill showed that the study’s participants who reported the most amounts of hugs had the highest levels of oxytocin. Also, the study participants with the most hugs had the lowest blood pressure.

Furthermore, Dr. David R. Hamilton, who specializes in biological and medicinal chemistry, says that, “The repetition of kind acts might have a cumulative effect on oxytocin production levels, at least if research on hugs is anything to go by. Oxytocin increase is a side effect of hugging. It’s actually been called the ‘cuddle chemical.’ I guess you could say that, ‘A hug a day keeps the cardiologist away!’”

Sources:
http://www.prevention.com/mind-body/emotional-health/doing-kind-acts-reduces-anxiety-study
http://health.usnews.com/health-news/news/articles/2013/01/24/acts-of-kindness-can-make-you-happier
http://www.huffingtonpost.com/david-r-hamilton-phd/can-kindness-cut-the-risk_b_799562.html