The main reason for sleep is to allow your mind to process all the happenings of the day. Your body should be pretty fine after a full day of being awake, so long as you can get your mind right. If you don't want to take a nap then try meditating for a little while. As a form of 'conscious' sleep, it's more time efficient than a nap. I meditate when I run so that's what I'd do, but that's not for everyone. 