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 executing this healthy plan is way easier said than done. If you’re looking for more motivation to get up and get moving, a new study from Northwestern Medicine might give you that extra push.The 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.This connection was independent of each person’s physical activity level, caloric intake, sleep timing, age or season. Researchers point to sunlight’s role in regulating our circadian rhythm as the explanation for its effect on BMI.”Light is the most potent agent to synchronize your internal body clock that regulates circadian rhythms, which in turn also regulate energy balance,” says study senior author Phyllis C. Zee, M.D. “If a person doesn’t get sufficient light at the appropriate time of day, it could de-synchronize your internal body clock, which is known to alter metabolism and can lead to weight gain.”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.If you spend the majority of your day sitting inside at a desk, you know how tough it is to squeeze in some sun. And although indoor lighting counts, most people work in poorly lit environments, making it hard to reach the minimum threshold that researchers say will help lower BMI.This connection between light and BMI has potential to open up new weight loss strategies. “Just like people are trying to get more sleep to help them lose weight, perhaps manipulating light is another way to lose weight,” says co-lead author Kathryn Reid, research associate professor of neurology at Northwestern University Feinberg School of Medicine.