Whether you’re a morning person or a night owl, you’ve probably wondered: is there an optimal time of day to work out? The debate between the benefits of an energizing AM sweat session versus an evening stress-relieving workout has raged on for ages. But the answer isn’t as black and white as you might think. Believe it or not, the time you choose to lace up your sneakers can impact everything from your mood to your metabolism. Surprising new research reveals how finely tuned your circadian clock is and how harnessing your body’s natural 24-hour rhythms can help you burn