It's not the water! Here's the real reason you wake up at 2 a.m.

You're snuggled up under the covers, everything seems peaceful… and suddenly, your eyes snap open. 2 a.m. No idea why. You glance at the clock, turn over, sigh… and sleep is gone. If this sounds familiar, don't worry: you're not alone! And no, it's not necessarily that glass of water you had before bed that's to blame.

There are several, often surprising, explanations for these nighttime awakenings. The good news is that once understood, they are easily corrected.

The real culprit: a body that rebalances itself at night