Does Tryptophan in Turkey Make You Tired?

Written by Nate Martins • November 20, 2018. Originally published on HVMN, adapted for use on Lorieb

Forks no longer clang against plates. Conversation lulls. Chairs scrape against the floor as family members make their way from kitchen table to Lazy-Z-Boy. The Thanksgiving feast is over. Now, eyelids drowse. Everyone starts to fall asleep, wine glasses are half full, football commentators hum in the background, crumbs stuck to mustaches flutter in the rhythm of each hot, heavy breath. Is this your Thanksgiving meal aftermath? Maybe your astute, know-it-all cousin points out that tryptophan, present in turkey (and many other foods) is causing everyone to fall asleep by 6pm.

You can tell them that’s just a myth. Tryptophan isn’t the reason your living room looks like an kindergarten nap time, it’s all the other stuff you’re eating alongside it.

What is Tryptophan?

It’s an amino acid. Amino acids form the building blocks of protein, the main structural and functional compound in the body. Tryptophan is one of nine essential amino acids, meaning it cannot be produced by the body and must be obtained directly through food.

This amino acid plays a part in some vital, bodily processes. It helps regulate nitrogen balance in adults and growth in infants. It also is important for production of creating niacin which is essential for creating serotonin. Serotonin is a neurotransmitter associated with sleep and melatonin levels. This is where the villainization of turkey comes in. But tryptophan isn’t just in turkey; it’s also in other high-protein foods. In fact, many foods such as seeds, cheese and soybeans, have more than turkey.

You’re Tired Because

You overate.

Yes, turkey can make you drowsy. But the other foods that contain tryptophan in high amounts don’t get the same bad rap as turkey. So what’s causing the sleepiness?

Really it’s mixing tryptophan-rich turkey with other carbohydrates–like, say, mashed potatoes and stuffing and bread and pie–that is to blame.

Consuming carbs triggers insulin release, which causes uptake of other types of amino acid into the muscles (but not tryptophan). This means that tryptophan levels are higher than usual, especially relative to other amino acids. Normally amino acids compete with one another for uptake into the brain, but when tryptophan is present at higher-than usual amounts, more of it gets in.

Without competition, the floodgates open, allowing more and more tryptophan to enter the brain. From there it’s used to produce serotonin and eventually, melatonin.1 Any big meal containing tryptophan and lots of carbohydrates can induce drowsiness. And of course other factors, like drinking alcohol, can also play a role in that sleepiness.

Even if you ate a large meal without any tryptophan, you’ll likely still be tired–especially if it’s rich in carbohydrates.2,3,4 Large portions of food force the body to digest, which requires significant energy use. You’ll get the signal from your brain to chill out while your gut kicks into overdrive. This feeling is likely unavoidable, because the parasympathetic nervous system (responsible for telling your heart to beat and your lungs to breathe) automatically triggers this process, informally known as “rest and digest.”

Tryptophan may play a role in post-meal tiredness, but it’s largely everything else you ate putting you into a food coma.

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