It's not just for kids -- even adults appear to benefit from a regular bedtime: Adults with varied sleep-wake times weigh more, have higher blood sugar, risk of disease -- ScienceDailyOf all three measures, however, regularity was the best at predicting someone's heart and metabolic disease risk, the researchers found. As one might expect, irregular sleepers experienced more sleepiness during the day and were less active -- perhaps because they were tired, Lunsford-Avery said. Researchers plan to conduct more studies over longer periods in hopes of determining how biology causes changes in sleep regularity and vice-versa. "Perhaps there's something about obesity that disrupts sleep regularity," Lunsford-Avery said. "Or, as some research suggests, perhaps poor sleep interferes with the body's metabolism which can lead to weight gain, and it's a vicious cycle. With more research, we hope to understand what's going on biologically, and perhaps then we could say what's coming first or which is the chicken and which is the egg."