Happy people do seem to be healthier, and happiness itself may cause good health. In fact, happiness may be as important a factor in overall health as someone's smoking habits [source: Veenhoven]. Worried about heart disease and stroke? Happiness appears to make people more resistant to both conditions. Don't want to catch a cold this year? One study that exposed subjects to a cold virus found that people who considered themselves happy were less likely to get sick -- and expressed fewer symptoms even if they did contract the virus [source: Carnegie Mellon University]. Dealing with depression? Get thee to a doctor -- studies show that depressed adults are 60 percent more likely to have type 2 diabetes, possibly because the stress hormone cortisol raises blood sugar levels [source: Katz].
Even among poor people whose needs for food and shelter aren't adequately met, there's a connection between how happy people are and how healthy they are. One study of more than 150,000 adults showed a more important link between happiness and health than basic needs (food, water, shelter) and health [source: Lynch].
Interestingly, happiness also seems to extend life -- if you're already healthy, that is. Among unhealthy populations, it doesn't seem to affect longevity. Think of happiness as a plastic sofa guard for your health: It protects your couch but can't fix what's already wrong with it. For independent seniors who live alone or with family, happiness predicts a longer life; those living in nursing care facilities (as a likely result of failing health) don't show the same correlation [source: Potts]. With these results in mind, it looks like happiness may be a preventive measure, not an antidote.
How much control you have over your life and work also influences your happiness -- and your health. For instance, people with easy access to medical information tend to be happier patients than those who don't. Workers who have little control over their jobs, or little say in how the job is performed, report lower levels of happiness as well.
So what can you do to up your happiness level? Studies indicate that happiness can be "practiced" or enhanced through meditation [source: National Institutes of Health]. Additionally, experiences -- such as traveling -- make us happier in the long run than acquiring possessions [source: Gordon].
And it doesn't take too long for the results to kick in -- increasing your happiness can show result in positive changes in your health in as little as three years [source: Center for the Advancement of Health].