A common assertion is that heavy consumption of turkey meat results in drowsiness, due to high levels of tryptophan contained in turkey.[50][51][52] However, the amount of tryptophan in turkey is comparable to that contained in most other meats.[17] Furthermore, post-meal drowsiness may have more to do with what else is consumed along with the turkey and, in particular, carbohydrates.[53] It has been demonstrated in both animal models[54] and humans[55][56][57] that ingestion of a meal rich in carbohydrates triggers release of insulin. Insulin in turn stimulates the uptake of large neutral branched-chain amino acids (BCAA), but not tryptophan (an aromatic amino acid) into muscle, increasing the ratio of tryptophan to BCAA in the blood stream. The resulting increased ratio of tryptophan to BCAA in the blood reduces competition at the large neutral amino acid transporter (which transports both BCAA and aromatic amino acids), resulting in the uptake of tryptophan across the blood–brain barrier into the cerebrospinal fluid (CSF).[58][59] Once in the CSF, tryptophan is converted into serotonin in the raphe nuclei by the normal enzymatic pathway.[54][56] The resultant serotonin is further metabolised into melatonin by the pineal gland.[10] Hence, this data suggests that "feast-induced drowsiness"— may be the result of a heavy meal rich in carbohydrates, which, via an indirect mechanism, increases the production of sleep-promoting melatonin in the brain.[54][55][56][57]