If you work out early in the day, you know, before 8 or 9:00 a. m. , it's going to accelerate that increase in body temperature and you'll feel more alert.There's also this beautiful phenomenon in circadian biology called entrainment whereby, let's say you're not a morning person. You hate mornings. If you force yourself to get up and exercise at say 6:00 am for three days in a row by the fourth day you'll naturally start waking up around that time because the circadian clock of the brain we call the super ...