Turkey does have the makings of a natural sedative in it, an amino acid called tryptophan. Tryptophan is an essential amino acid, meaning that the body cannot manufacture it. The body has to get tryptophan and other essential amino acids from food. Tryptophan helps the body produce the B-vitamin niacin, which, in turn, helps the body produce serotonin, a remarkable chemical that acts as a calming agent in the brain and plays a role in sleep. So you might think that if you eat a lot of turkey, your body would produce more serotonin and you would feel calm and want a nap.