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Freshly Baked Science

Does Turkey Make You Sleepy?

22nd December 2018

At 5pm on Christmas Day, there is the same scene in almost every household… every member of the family slumped on the sofa, ‘resting their eyes’. There’s no denying that everyone feels sleepy after eating Christmas dinner and it’s widely believed that the turkey is to blame…

The theory that the turkey causes you to become sleepy comes from the fact that it contains a lot of an amino acid called Tryptophan, which is the basis of brain chemicals that make you tired. But the fact is that turkey doesn’t actually make you any sleepier than any other food.

Tryptophan is a component of serotonin, which can be converted into melatonin- a sleep-regulating chemical. Logically, if you eat more food with tryptophan in it, you’re likely to feel more tired, but the tryptophan competes with other amino acids to get into the brain so not all of it will reach the brain. You’d have to eat a huge amount of turkey to build up a sufficient amount of tryptophan (we’re not judging).

It’s more likely to be the large amount of carbohydrates which cause you to be ready for bed a couple of hours after you’ve eaten. All the mash, roast potatoes, Yorkshire pudding, bread sauce, stuffing, etc. can really take their toll. When you eat carbohydrates, it triggers the release of insulin. Insulin removes all amino acids, except tryptophan, from the blood. This gets rid of any competitors to cross the blood-brain barrier, which allows more tryptophan to enter the brain. This tryptophan is then used to make serotonin, which is converted into melatonin.

So, to summarise, it is tryptophan which makes you sleepy after eating Christmas dinner, but the turkey isn’t to blame! While turkey and other protein-rich foods are quite high in tryptophan, there is still a lot of competition to get into the brain. If you eat a lot of carbs with your turkey, insulin is released which removes the competition, allowing lots of tryptophan into the brain!

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