The results of earlier studies have been mixed, with some finding that unhappiness causes illness and others showing no link, Dr. Fischhoff said.
An editorial accompanying the study in The Lancet noted that it had “the largest population so far in happiness studies,” and praised its statistical methods. But it also said more research was needed.
Professor Peto said he doubted that the new study would change many minds because beliefs about the perils of unhappiness are so ingrained.
“People are still going to believe that stress causes heart attacks,” he said.