Author Austin Kleon makes this observation in his book Keep Going, which he backs up with what most scientists who have studied what sleep does for us say: that while we sleep, our mind uses that time to separate what it needs from what it doesn't, sorting it all away into memory files and clearing the cache of what it doesn't need to keep around.
That's why we dream. Dreams are part of that sorting out. It's why many dreams feature weird amalgamations of what happened earlier in the day with memories from 10 years ago: our minds are working through our experiences, processing them and storing them for later.
Sleep also factors into one's creativity. Those who consider themselves artists of any kind could probably tell you the positive difference that sleep can make to the creative process.
First, it's simply rest for your mind and body. You need that for a lot of different reasons. The body needs time to sort itself out just like the mind does.
Second, when your brain gets that "tidying up" time, it can literally clear your mind of what you don't need so that you can think more clearly about what you're working on.
Then Kleon adds his own preference, which is near and dear to my own:
Me, I like the "caffeine nap": Drink a cup of coffee or tea, lie down for fifteen minutes, and get back to work when the caffeine has kicked in.This is pretty much exactly how I take naps, although it's hardly ever an intentional thing. I tend to enjoy a coffee or two in the afternoon. When I'm sitting on my couch, my body might say, "Hey, let's doze off for a little bit. I need a break." And so I lay my head back and the next thing I know 20 minutes have passed. Then I finish my cup and continue with my day, often feeling a boost in energy and a renewed resolve to work on something.
Of course, this isn't the only way to do it. Far be it for me to dictate limitations on nap options.
But if you're a creator of some kind and are feeling stuck, maybe all you need is a nap.