Do find yourself reaching for chips, cookies, and candy far more often when you haven’t gotten enough sleep? If you’ve had the nagging suspicion that it’s harder to resist junk food when you’re sleep deprived, you’re right. Adults need a full seven to eight hours of sleep for the body to run at peak efficiency. When you get less, the brain starts changing the way hormones are released. The result—junk for cravings and unwanted weight gain.