The advice: Sam Sugar, MD, says this comes up all the time at the Pritikin Longevity Center & Spa, where he's the director of sleep services, and where twice-daily exercise is part of the program. Sugar points out that the scientific literature is extremely clear about the dangers of sleep loss. "Even one night of short-changed sleep can be bad for your health," he says, and excessive sleeplessness can result in increases in blood pressure, cholesterol and blood sugar—as well as weight gain. Missing one or even two workouts doesn't have the same magnitude of negative effects. At the minimum, Sugar recommends getting six and a half to eight hours of sleep every night, while squeezing in exercise at least three times a week.