Tryptophan's association with sleepiness and Thanksgiving food coma

Tryptophan, an essential amino acid found in protein-rich foods like turkey, has been linked to sleepiness and the infamous Thanksgiving food coma. Although turkey contains tryptophan, it is not significantly higher in tryptophan compared to other meats or proteins. Furthermore, it would require consuming a massive amount of turkey to reach the dose of tryptophan that has been shown to have sedative effects. The idea that foods with tryptophan, like turkey and milk, cause drowsiness is based on the fact that tryptophan is a precursor to serotonin and melatonin, which are associated with sleep. However, tryptophan needs to cross the blood-brain barrier to affect sleepiness, and its transport is influenced by the ratio of tryptophan to other large neutral amino acids. Carbohydrate-rich sides, like mashed potatoes, can alter this ratio and potentially increase the levels of tryptophan that enter the brain. Overall, while tryptophan is present in turkey, it is not the sole contributor to post-Thanksgiving sleepiness.