If you're needing a bit of help nodding off, the trick could be an added dose of tryptophan. The amino acid works to trigger the release of serotonin, which helps you feel calm, relaxed, and, well . . . sleepy. And believe it or not, turkey is not the only nor the leading source of trytophan — scroll through to see the best food sources of this natural sleep aid, with easy, healthy recipes to make at home before bedtime.