Happy people have an advantage over unhappy ones–they may be healthier and may live longer. An extensive review of literature using seven types of evidence indicates that high subjective well-being (SWB), such as life satisfaction, optimism, and positive emotions, causes better health and longevity. The review, published in Applied Psychology: Health and Well-Being (2011), examined 160 studies which showed compelling evidence that positive feelings predict health and longevity.
The findings of the review, based from seven types of evidence, are summarized below:
Longitudinal studies. These studies, which have large sample sizes and have followed participants for a decade or more, revealed that SWB was related to lower mortality rate in both healthy and diseased populations. Positive moods such as joy and happiness, life satisfaction, hopefulness, optimism, and a sense of humor were associated with reduced risk of mortality and predicted longevity.
Physiology and health. Moods and emotions are associated with biological markers such as blood pressure, cortisol, and inflammation. Studies found that pessimists have higher blood pressure levels. Anger and hostility were related not only to the development of cardiovascular disease, but also to disease progression and inflammation. Stress predicted lower levels of immune response; whereas, positive affect strengthened immunity. Positive affect was associated with greater social connectedness, perceived social support, and greater probability of performing healthy behaviors.
Experimental manipulations of emotions. In experimental studies, positive and negative moods are induced which are then measured. Research showed that participants exposed to positive mood induction had quicker cardiovascular recovery after a stressful task than subjects who were exposed to neutral and negative mood inductions. Studies also revealed that couples who were generally higher in hostility had slower wound healing than low hostile couples, as well as more tumor necrosis and a poorer immune response.
Animal studies. Animals are used in experimental research to obtain information about how certain positive and negative situations affect their health and longevity. Studies revealed that socially-stressed monkeys developed more extensive atherosclerosis than unstressed ones. Stress, threatening human behavior, and isolation suppressed the immune system of monkeys, chickens, and pigs. Pigs that learned a mastery task to obtain rewards, giving them some control over their environment, later showed quicker wound healing and carcass quality.
Quasi-experimental studies in natural settings. Studies in quasi-experimental studies suggest that events and disasters are associated with cardiovascular and immune changes. Disasters, bereavement, and observing exciting sports events can trigger cardiac deaths in vulnerable individuals. Further, people with work overload and worry showed higher cortisol response at awakening and on weekdays but not on weekends.
Interventions that influence SWB. Researchers found that transcendental meditation and progressive relaxation reduced blood pressure over a 3-month follow-up period, compared to a control group. People who wrote about intensely positive experiences had fewer health center visits for illness during the following 3 months, compared to people who wrote about a control topic. Patients who suffered from myocardial infarction, who received Type-A counseling (for Type A behavior) in addition to traditional cardiac counseling, were less likely to die within 5 years.
SWB`s impact on quality of life and pain. Studies showed that positive emotions were related to lower pain and greater tolerance for pain. Patients suffering from fibromyalgia and rheumatoid arthritis reported less pain with positive mood induction while women reported less pain to heat stimuli when looking at photos of their partner.
In sum, these converging studies form a compelling proof that SWB, such as happiness, causally influences health and longevity.