How does marriage affect physical and psychological health?

"This paper examines an accumulating modern literature on the health benefits of relationships like marriage. Although much remains to be understood about the physiological channels, we draw the judgment, after looking across many journals and disciplines, that there is persuasive longitudinal evidence for such effects. The size of the health gain from marriage is remarkable. It may be as large as the benefit from giving up smoking"--Forschungsinstitut zur Zukunft der Arbeit web site.