Stress test for energy

A crazy day at the office can cause production of the hormone cortisol to skyrocket, says SELF contributing expert Catherine Birndorf, M.D., associate professor of psychiatry at New York-Presbyterian Hospital. "Once whatever's stressing you out is over, cortisol levels go back to normal, but that drop leaves you feeling fried."

Taking mini time-outs during the day—texting a friend, updating your Spotify playlist or chatting with a coworker—can help keep stress freak-outs in check so you won't be completely zonked by 6 p.m

Unappetizing, but true: Urine should be pale yellow; any darker means you're dehydrated. Even mild dehydration can make you feel wiped and less able to focus, finds research in The Journal of Nutrition.

As for what you sip, it doesn't have to be water. Any liquid, even coffee or alcohol, counts. (Though too much spiked stuff won't exactly keep you on your toes.)

If you and the snooze button are besties, you're not sleeping enough. Docs recommend seven to nine hours of shut-eye a night, but everyone's different. You'll know you've found your Z spot when you can rise and shine without alarm assistance.

Particularly tired? Sitting quietly (no tech distractions!) or napping for 90 minutes can help your brain process new info, a Vision Research study finds.

Understandable! But it could help explain why you're so weary.

Before you caffeinate (again), try this: Get up and go for a stroll, even if it's just to grab lunch or run errands. Moving for as little as 20 minutes a day can increase energy levels by 20 percent, research shows.