If your spouse expects good things to happen, you may be reap better health as a result.

Having an optimistic spouse predicted better mobility and fewer chronic illnesses over time, even above and beyond a person's own level of optimism, according to a new University of Michigan study of 3,940 adults.

Researchers used data from the Health and Retirement Study, a national study of American adults over age 50. The study's 1,970 heterosexual couples were tracked for four years and reported on their physical functioning, health and number of chronic illnesses.

"A growing body of research shows that the people in our social networks can have a profound influence on our health and well-being," said Eric Kim, a doctoral student in the U-M Department of Psychology and the study's lead author. "This is the first study to show that someone's else optimism could be impacting your own health."

Past research found that social support may partly explain the link between optimism and enhanced health. Optimists are more likely to seek social support when facing difficult situations and have a larger network of friends who provide that support.

In close relationships, optimism predicts enhanced satisfaction and better cooperative problem-solving, like focusing on ways to protect against declining health.

"So practically speaking, I can imagine an optimistic spouse encouraging his or her partner to go to the gym or eat a healthier meal because the spouse genuinely believes the behavior will make a difference in health," Kim said.

The study's other authors included William Chopik, a graduate student in psychology, and Jacqui Smith, a professor in the Department of Psychology and Institute for Social Research. The findings appear in the current issue of Journal of Psychosomatic Research.