“Eating turkey makes you especially sleepy because of tryptophan”

Many people have heard that the tryptophan in turkey is responsible for that drowsy feeling after a big holiday meal. This common belief likely stems from the fact that turkey does contain tryptophan, an amino acid that plays a role in the production of serotonin and melatonin, both of which are involved in regulating sleep. The idea seems to make sense on the surface: eat turkey, get tryptophan, feel sleepy.

However, the scientific evidence doesn't quite support turkey as a unique sleep inducer. While turkey does contain tryptophan, it doesn't have significantly more of this amino acid than other common meats like chicken or beef. In fact, many other foods, including cheese, nuts, and even chocolate, contain comparable or higher levels of tryptophan. For tryptophan to have a noticeable effect on sleepiness, it needs to cross the blood-brain barrier, and its absorption can be hindered by the presence of other amino acids, which are abundant in protein-rich foods like turkey.

The persistent belief that turkey causes post-meal lethargy is likely due to several other factors often associated with large holiday feasts. The sheer act of overeating, regardless of the food, diverts a significant amount of blood flow to the digestive system, which can leave you feeling sluggish. Furthermore, holiday meals often involve alcohol consumption, which is a known sedative, and a high intake of carbohydrates. Carbohydrates trigger the release of insulin, which can help clear other amino acids from the bloodstream, making it easier for tryptophan to reach the brain. So, while tryptophan is present in turkey, it's the overall celebratory indulgence that's more likely to blame for your post-Thanksgiving nap.