You should try: Just after waking up
Exercise at any time of the day will help you sleep better than no exercise at all, found the National Sleep Foundation, but there are a few reasons why working up a sweat in the morning might make for an even more restful night. First, sleep experts say that exposure to daylight soon after waking (during a run, bike ride or even a drive to the gym) has the effect of putting a time stamp on your brain: It reminds it when you woke up and when you need to power down at night. Health researchers at Appalachian State University have also found that morning exercise reduces blood pressure and causes an additional 25 percent dip at night, which has been correlated with better sleep. Despite these benefits, exercise can't substitute for sleep, so make sure your Zumba class doesn't cut into your seven mandatory hours.