Why is it unhealthy to be in a miserable marriage?

Most of us have heard that married people are healthier than their single counterparts. But new research shows that the state of your union matters more than just being married.

One recent study found that couples living in a miserable marriage are 25 times more likely to suffer a major depression than those in a happy marriage. And if you have suffered a heart attack, a bad marriage could increase your risk for a second attack. It can also cripple your recovery from cancer and weaken your immune system. Even a single bad argument can raise your blood pressure sharply, putting your health on the line.