Get outdoors.
Your body’s natural circadian rhythm is actually slightly longer than 24 hours, which means your sleep clock naturally shifts a few minutes each day–making it a challenge to consistently wake up at the same time each morning. Exposing yourself to natural light–not indoor light–each morning will help you reset that clock daily. “Doing things in brighter light does improve alertness and performance,” Sharkey says, adding that you don’t even have to do it in one fell swoop: As long as you’re accumulating between 15 and 60 total minutes of outdoor time daily by lunchtime, you’ll be in better mental shape.