Today I found out turkey does not make you drowsy after you eat it.

Now to be clear, turkey does contain tryptophan.  Tryptophan is an amino acid which the human body doesn’t naturally produce, but is essential to proper body function and, thus, must be acquired from food.  The reason tryptophan is tied to drowsiness is that it is used by your body to create serotonin.  Serotonin, among other things, acts as a calming agent in the brain and plays a key role in sleep.  So with turkey containing tryptophan, one would logically say it would make you sleepy after you eat it… except, this isn’t actually the case.

So, why not?  Primarily because of how we eat turkey and more importantly how the body deals with tryptophan.  If you tend to eat turkey on a completely empty stomach and don’t eat anything else but a little turkey, then there’s a very small chance that the tryptophan in the turkey will make you a little drowsy right after you eat it.  Add it to a sandwich or have it with some mash potatoes or really pretty much any other food eaten at the same time or just eat it on a non-empty stomach and it won’t be the turkey that is making you drowsy if you feel drowsy after.

It turns out, tryptophan needs to not only be taken on an empty stomach to have any instant effect, but also with little to no other amino acids or protein present in order to make you drowsy after you eat something that contains it.  Given that there is a lot of protein in turkey and other amino acids, even if you are a bit malnourished, you are not likely to get drowsy from the tryptophan after you eat turkey, though it will increase your body’s store of the tryptophan.

What’s going on here is that when there are a lot of amino acids around, this causes competition among the amino acids as far as crossing the blood-brain barrier.  Tryptophan is a particularly bulky amino acid so it ends up being at the back of the line, so to speak, and will generally stay there until those other amino acids are gone or, at the least, until quite a lot of them are gone so the ratio of tryptophan to those other amino acids is drastically increased.

So why do you get drowsy after, say, eating turkey on Thanksgiving or the like?  Well, there are a lot of reasons, but primarily because, with your holiday meal, you likely just crammed a couple days worth of food into your body in the span of an hour or so, possibly with some alcohol, which is a central nervous system depressant that has a mild sedative effect.  Also, with a full stomach, your body directs blood away from your central nervous system and other organ systems to help with your digestive system.  More than anything, this is probably causing most of the drowsiness after a large turkey dinner, such as on Thanksgiving or Christmas or the like.

The “drowsy” effect is even more noticeable when your food contains quite a bit of various fats, which take a lot of energy to digest, and carbohydrates. Carbohydrates in particular release insulin.  This results in various amino acids being more or less swept out of your blood, being absorbed into your muscle cells, and thus the tryptophan to other amino acid ratio increases quite a bit, giving the tryptophan a better shot of crossing the blood-brain barrier and raising your serotonin levels.

Now there is typically always a nice store of tryptophan in your body at any given time due to the fact that it is not only prevalent in turkey, but also higher levels than in turkey per ounce can be found in chicken, beef, pork, cheese, chicken eggs (which contain nearly four times as much tryptophan per ounce over turkey), sunflower seeds, and many types of fish; it also is found, in lesser or similar amounts as in turkey, in milk, beans, sesame seeds, lamb, wheat flour, chocolate, white rice, oatmeal, potatoes, and bananas, among a lot of other foods.  So your body is typically stocked full of tryptophan most of the time and eating some turkey isn’t going to significantly change your body’s store, though it will add some.

So, if you want to point to a specific food that can make you quite drowsy, it would be things high in carbohydrates such as pasta, mashed potatoes, breads, and the like;  these not only cause your body to direct more blood towards your abdomen and away from other organ systems, which will make you drowsy, but also result in some of the tryptophan hanging out in your body to actually get a chance to make it passed the blood-brain barrier to eventually produce some serotonin.

If you liked this article, you might also enjoy our new popular podcast, The BrainFood Show (iTunes, Spotify, Google Play Music, Feed), as well as:

• Thanksgiving Facts Roundup
• Where the Phrase Quitting “Cold Turkey” Comes From
• Why Three Strikes in a Row in Bowling is Called a “Turkey”
• Why Turkeys Are Called Turkeys
• Joe Engel and The Shortstop Who was Traded for a Turkey

Bonus Facts:

• For a nice healthy way to make yourself drowsy (as in not by stuffing yourself), boost your serotonin levels by eating a small, all-carbohydrate snack (no more than 30 grams of carbohydrates is necessary).  This, in combination with the tryptophan already stored in your body, will give you a big boost in serotonin levels, according to Elizabeth Somer, MA, RD.  Appropriate snacks here would be a few Fig Newtons, half a bagel with a little honey, a couple cups of non-buttered popcorn, etc.  According to Somer, eating these small snacks right before bed has been shown to help significantly in getting a good night’s rest and is a healthy way to do so, unlike stuffing yourself or the like.
• Serotonin is a neurotransmitter, which also can in turn be converted to melatonin, which is a neurohormone that is also used to regulate your sleep/wake cycle.  Serotonin gets produced by tryptophan crossing the blood-brain barrier into the central nervous system.  There, it is eventually converted into serotonin.
• Ben Franklin fought hard for the Turkey to become the nation’s official bird, but he obviously lost out to the supporters of the Bald Eagle.  His case for the Turkey being the national bird on the Great Seal is laid out in the following letter to his daughter Sarah Bache:
  “For my own part I wish the Eagle had not been chosen the representative of our country. He is a bird of bad moral character. He does not get his Living honestly. You may have seen him perched on some dead tree near the river, where, too lazy to fish for himself, he watches the labor of the Fishing Hawk; and when that diligent Bird has at length taken a fish, and is bearing it to his nest for the support of his mate and young ones, the Eagle pursues him and takes it from him.
  With all this injustice, he is never in good case but like those among men who live by sharping & robbing he is generally poor and often very lousy. Besides he is a rank coward: The little King Bird not bigger than a Sparrow attacks him boldly and drives him out of the district. He is therefore by no means a proper emblem for the brave and honest Cincinnati of America who have driven all the King birds from our country…
  “I am on this account not displeased that the figure is not known as a Eagle, but looks more like a Turkey. For the truth the Turkey is in comparison a much more respectable bird, and withal a true original native of America . . . He is besides, though a little vain & silly, a bird of courage, and would not hesitate to attack a grenadier of the British Guards who should presume to invade his farm yard with a red coat on.”
• So how much tryptophan should you intake on a daily basis?  “If you’re getting even one serving of 3 ounces of meat, chicken, or fish; a couple of glasses of milk or yogurt; or if you’re eating beans and rice, you will get all the amino acids you need and in there will be the tryptophan,” says Elizabeth Somer, MA, RD.
• In the 1980s, tryptophan became a popular supplement among those suffering from insomnia and those wishing to fall asleep quicker.  These supplements typically contained about as much tryptophan as is present in two pounds of turkey meat and were taken daily.  This was later linked to an outbreak of eosinophilia-myalgia, which causes muscle pain and sometimes death.  As a result of this, the FDA banned tryptophan supplements, even though it was unlikely that it was the tryptophan itself causing this, rather, contaminated supplements.
• Tryptophan was first isolated by Frederick Hopkins in 1901.  He did so through hydrolysis of Casein, which contains about 4-8 grams of tryptophan per 600 grams of Casein.