As is learning that sometimes you can make time for you.

Hence the "as long as it's not abused" part of my comment. Of course you can't call out every time you have a deadline or a test or you're feeling a little stressed.

But the occasional "look, I'm not physically ill but I just need a day" is fine. It's exactly what people are already doing, except you don't need to hang your head upside-down over the side of your bed to make it sound like you have a cold when you make the call.