Recessions are usually regarded as nasty times, but soaring unemployment and sputtering stock markets do have an unexpected sunny side. They make us healthier.

Christopher Ruhm, an economics professor at the University of North Carolina at Greensboro, has spent more than a decade studying the effects of economic booms and busts on our well-being. He’s examined recessions in the U.S., Canada and other industrialized countries going back to the 1960s, and he’s boiled his findings down to a simple formula—a one percentage point rise in unemployment causes the death rate to fall by half a percent and the overall number of medical problems to fall 1.5%. “I’m not advocating recessions,” says Ruhm. “But it seems that when times are bad and so many things are beyond our control, people decide that what they can take charge of is their own health.”

A recession’s healthy impact begins with a safer environment. When economic output slows down, air pollution falls. That helps people with breathing and circulatory problems. In addition, the fewer people with jobs, the emptier the roads. So car crashes go down.

But it’s not just these passive benefits that help to cut the death rate in bad times. Ruhm’s research indicates that people make a conscious decision to live healthier lives. Since there is less work, we have more time for exercise. As budgets tighten, we buy less booze, quit smoking and eat out less often.

Unfortunately, when the good times return, so do our old habits. The death rate then rises 0.4% for every one percentage point fall in the unemployment rate.

Blame it on longer hours. When work gets busy, we drink and smoke more to unwind. We also get fatter,says Margot Shields, an analyst at Statistics Canada in Ottawa, who has studied the link between longer work hours and health. Sixty-hour work weeks don’t leave much time to head to the gym.

Of course, there’s a simple solution to having robust health no matter which direction the stock market is headed. Eat healthier food, drink less, and don’t let all that paperwork piling up on your desk stop you from hitting the treadmill.

Better yet, make sure you take a vacation every year, says Dr. Mel Borins, an associate professor at the University of Toronto’s Department of Family and Community Medicine, and author of Go Away: Just for the Health of It. People who take a regular vacation are less likely to suffer heart attacks, he says. “Leisure time may be just as important as diet and exercise in keeping us well.”