8 Surprise Reasons You're Still Tired

You usually pop your all-day allergy pill as soon as you get up, believing the manufacturer's promise that you'll be symptom-free until bedtime. And you will —but while your head will feel clearer, it may also feel heavier, and you'll find it hard to stay awake. This is because antihistamines—even "nondrowsy" or non-sedating versions —can make people sleepy, says Sakina Bajowala, a board-certified allergist and immunologist with a private practice in North Aurora, Illinois. She advises taking your 24-hour-action pill at bedtime. You'll sleep off the immediate drowsy side effects, and the meds will continue to keep you sniffle-free throughout the next day.