Turkey’s effect on sleepiness


Thanksgiving is here! It is a joyous time to hang out with family and friends and gorge oneself on mashed potatoes, stuffing, pie and especially turkey. After this grandiose feast, a familiar feeling comes over everyone. That warm, sleepy feeling that beckons one to the land of dreams. But what causes this? What causes the lethargy to take over? Why are so many people sleepy after Thanksgiving dinner?

The most likely suspect is the centerpiece to every Thanksgiving feast: the turkey.  Going down to the microscopic level, turkey is very rich in the amino acid tryptophan. This amino acid is converted by the human biological system to form niacin, which is a B-vitamin that is further used to produce serotonin. Serotonin is a chemical that is found in the brain that helps to put people in a relaxed and happy mood. Serotonin is then converted to the hormone melatonin, which is responsible for the regulation of sleep cycles. Since turkey is high in tryptophan, it is only reasonable to assume that the drowsiness felt after Thanksgiving dinner is due to the excess melatonin hormone created by the excess amount of tryptophan. Case closed, right? Wrong.

The amount of tryptophan in turkey, while high, is not a staggering amount.  There is, in fact, more tryptophan found in chicken and cheddar cheese than there is found in turkey. Plus, very little of the tryptophan amino acids actually make it into the brain due to the blood-brain barrier, which heavily regulates the amount of amino acids that are able to enter the encephalon, or brain. Due to the lack of an overwhelming amount of tryptophan and its inability to enter the brain all at once, it is safe to say that turkey is not the sole cause of the Thanksgiving after-effect.  But if turkey does not solely cause this phenomenon to happen, what then amplifies the effects of the tryptophan found in the turkey?

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The real culprit of the Thanksgiving snooze is none other than the carbohydrates found in such foods as pie, mashed potatoes, and cranberries. The flood of carbohydrates into the body’s system after Thanksgiving dinner causes a spike in insulin production. This insulin causes many amino acids to be removed from the blood–all except tryptophan. With very few amino acids in the blood, the tryptophan is able to enter the brain in larger quantities and trigger a large-scale production of melatonin. Then, voila! The excess amount of melatonin causes a feeling of great weariness to take over.  

Therefore, to avoid feeling tired after feasting this Thanksgiving, the best course of action to take would be to cut down on the quantity of food consumed.  This will keep insulin as well as melatonin levels down, thus maintaining alertness.  If this advice is followed then neither tryptophan nor its accomplice insulin will spoil your post-Thanksgiving festivities.          




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