From a large, six-year study of Greek adults, we have come to know that men who took naps at least three times per week had a 37 percent lower risk of heart-related death. Not only that, it is found that napping increases a person's cognitive functioning, allowing him to do better in various tasks. It seems that people who take regular naps are able to learn TWICE as much as those that don't.

If I may make a guess, I believe you've not been taking naps. So rest. It'll help you to save time, learn more, work better and live longer.

Ref:
psychologytoday.com/blog/beautiful-minds/201002/take-nap-it-may-boost-your-learning-capacity-among-other-good-things?page=2

psychcentral.com/blog/archives/2010/02/23/go-take-a-nap/