A new study suggests that married people are healthier than those who are single. The study was conducted at Carnegie Mellon University and published in Psychoneuroendocrinology. To conduct the study, researchers collected saliva samples from 572 healthy adults aged 21-55 over three non-consecutive days. Multiple samples were taken during each 24-hour period and tested for cortisol. Researchers found that married individuals had lower levels of the stress hormone cortisol than those who never married or were previously married.