What Is Tryptophan—And Does Turkey Really Make You Sleepy?

We all have our own Thanksgiving rituals, but the day usually looks something like this: Wake up, watch the parade and then some football, eat a massive amount of delicious food, and fall into an all-night food coma.

A lot of that food coma gets blamed on the tryptophan in turkey, but is it really this mysterious compound that makes you sleepy? Let’s fact-check Thanksgiving dinner’s biggest legend.

What Is Tryptophan?

Tryptophan is actually a type of amino acid a.k.a. the molecules that build proteins in our bodies. Turkey contains a number of amino acids, including tryptophan, threonine, isoleucine, and leucine. Our bodies can produce some amino acids (called ‘non-essential’), but we have to get others (called ‘essential’) from food.

Tryptophan is an essential amino acid that, in addition to building proteins, also synthesizes the neurotransmitter serotonin. So what does that have to do with your post-gobble slumber? Serotonin (which is often called the ‘feel good’ hormone) helps regulate your body’s sleep patterns by producing the hormone melatonin, which your body releases when it’s time to settle down for the night, explains says Jackie Ballou, R.D.

So that explains that! Right? Er, not so fast.

Myth Busting Tryptophan

There’s a catch: Turkey doesn’t actually contain any more tryptophan than other types of poultry, says Ballou. You can even find tryptophan in foods like soybeans, yogurt, eggs, and cheese—and none of these foods, including turkey, contain enough of the amino acid for it to have a sedative effect. Plus, the other amino acids in turkey counterbalance the tryptophan’s sleepy effects.

To put it in perspective, three ounces of turkey contains approximately 250 mg of tryptophan. To really feel the effects of the stuff, you’d have to consume the nutrient on its own and in a much higher amount. (Tryptophan supplements, which can support sleep, mood, and relaxation, usually contain about 1,000 milligrams.)

Related: 8 Possible Reasons Why You’re Exhausted All The Time

What does cause you to feel so tired after your Thanksgiving feast, then? All of the calories! When you gorge yourself with stuffing, pie, turkey, and potatoes, your body devotes tons of its energy to digesting it all, says Ballou. Plus, many of the Thanksgiving foods we love are really high in carbs—so they’ll make your blood sugar soar and then crash, and leave you half-asleep on the couch not long after you eat.

But hey, Turkey Day comes but once a year—so enjoy the food, relish the company, and bask in the food coma.

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