Some like to get it over with first thing in the morning; some look forward to doing it after work. Now comes research from the University of California, Los Angeles’s Brain Research Institute suggesting that the best time to exercise is afternoon, because afternoon exercise has a more potent (and good) influence on our internal body clocks. OK, to be precise, the researchers learned that the best time for mice to exercise is afternoon, but mice and humans have sufficiently similar internal body clocks that the scientists are persuaded. Writing in the New York Times, Gretchen Reynolds reports that the researchers found that mice that ran, at any time of day, produced more proteins in their internal clock cells ( a good thing) than mice who didn’t run. The difference in protein levels in the runners and non-runners was slight, however. When the researchers looked the difference in internal clock setting proteins in mice who ran at different times of day, they found that those who ran in the afternoon produced significantly more proteins than those who ran at other times. What does that mean for humans? For humans, especially older humans who have trouble getting to sleep and staying asleep, exercising in the afternoon may charge the batteries of your internal clock, helping you sleep at night and stay awake in the daytime. Read more from the New York Times. Read an abstract of the study here.