You know your day would be way more efficient if you could just drag yourself out of bed before work and fit in your workout. But morning are good for some things: a new study draws a connection between when you get your daily dose of sunlight and your BMI. An April 2014 study of 54 participants (men and women with an average age of 30) found that people who got the majority of their daily light exposure in the morning had a significantly lower BMI than those who didn’t get much exposure until later in the day. Researchers point to sunlight’s role in regulating our circadian rhythm as the explanation for its effect on BMI. To synchronize your internal body clock properly, aim to get your biggest dose of natural light between 8 a.m. and noon. Only 20-30 minutes is enough to positively affect BMI. That means a quick morning run, walking your dog, or even walking to work will not only benefit you for the obvious reasons physical activity will, but also give you that light exposure when your body could use it most.