Whoever coined the term "beauty sleep" didn't warn us of all the rigorous steps we'd need to take to live up to it. It's easy enough to put your head on the pillow, doze off, and call it a day, but the beauty part only comes when we take measures to ensure it does, from a nightly skin-care regimen to humidifiers — and even the material of those pillowcases you're snoozing on.