A British study followed women over 10 years and found that unhappiness and stress were not associated with increased mortality.
Even though poor health can cause unhappiness, sad people don’t die earlier than happy ones.
The researchers controlled for health problems, socioeconomic status, lifestyle factors and smoking and basically found that being sad does not increase your risk of dying from cancer or heart disease.
However, being unhappy most definitely affects quality of life and can lead to other unfortunate behaviours such as alcoholism, drug abuse, smoking and of course, depression and suicide.
Perhaps happiness alone doesn’t save you from cancer or heart disease, but the indirect relationship between unhappiness and ‘risky behaviour’ just might.