Think marriage is stressful? Try being unmarried. That’s the implicit message from researchers at Carnegie Mellon University, who are convinced that married people have lower levels of the stress hormone cortisol than unmarried. A Carnegie Mellon news release reports that when researchers studied saliva samples (taken over three consecutive days) from 572 healthy adults aged 21-55, they found that married participants had lower cortisol levels than the never married or previously married people. The researchers also compared each person’s daily cortisol rhythm — typically, cortisol levels peak when a person wakes up and decline during the day. Those who were married showed a faster decline. Why do we care? For one thing, lower cortisol levels are associated with less heart disease, and longer survival among cancer patients.