Nonfat Popcorn
The carbohydrates in nonfat popcorn help bring the amino acid tryptophan into your brain, where it's used to make a sleep-inducing neurotransmitter called serotonin. Since eating a heavy meal within two hours of bedtime can keep you awake, low-calorie popcorn (just 93 calories in three cups popped) is a great late-night snack. Choose plain, fat-free popcorn and jazz it up with some curry powder.
