What do you think about taking a nap? How about sleeping in?

I usually have a nap, after eating lunch or getting tired while I study. That is why I feel better like recharging energy and emptying my head in order to do remain tasks. Coffee is also good drinks to wake me up, but it also makes me be a little exited, when I drink a lot. Moreover, I sometimes cannot sleep on time, when I drink it late time. So I prefer having a nap, around 10 minutes, if it is allowed. I try to go to bed at the same time but I sometimes feel more to do something and to sleep in. After then, I regret that I do last night. Actually, I do not do any special thing after I lie on the bed. Then one day, I read an article about this, and it really matched with my situation. It says that many people sleep in when they get some stress or feel emptiness. Because they want to get rewards and fill their minds that they could not do during a day. Even though I know the psychological reason, I still often sleep in on these situations.