(Inc.) — Less than half of American small business owners will take a vacation this summer, down from 67 percent in 2006, according to a recent American Express survey. Why so few? Many cited their busy work schedules (37 percent) while others claimed that they simply couldn’t afford it (29 percent). Sixteen percent said that they just don’t vacation at all. But recent research suggests that vacation is more important than you may think—both for the health of the entrepreneur, as well as the health of the business. The Framingham Heart Study, for example, monitored women’s health over the course of 20 years. The research revealed that women who took only one vacation every six years were nearly eight times more likely to develop coronary heart disease. Another study reported by The New York Times in 2008 found that men who did nottake a vacation at least once a year had a “21 percent higher risk of death from all causes and were 32 percent more likely to die of a heart attack”.