Turkey is a staple of any Thanksgiving meal in the United States. It is very common that people overconsume turkey as well as other foods like stuffing, mashed potatoes, and gravy. People think that consuming turkey (because of the amino acid tryptophan) is what makes them sleepy after Thanksgiving dinner. But is that really what makes people sleepy?
Neurotransmitters
L-tryptophan is an amino acid that is a precursor to serotonin and melatonin. They are neurotransmitters that have specific functions during the sleep cycle. Just from the surface, it makes sense that tryptophan is the reason why people fall asleep after consuming a large meal consisting of turkey; however, that is not the case. In order for your stomach to break down the turkey in the stomach, move it to the small intestines, absorb the amino acids, and raise L-tryptophan blood levels to a significant point to induce an upregulation of serotonin and melatonin takes hours. So, what makes you tired immediately after Thanksgiving dinner?
There are two possibilities that could cause drowsiness. The first is reactive hypoglycemia, which is a condition where your blood sugar drops due to consuming food, and in this case an overconsumption. Insulin is released whenever there is food consumed (especially carbohydrates and sugars), and the role of that insulin in the blood is to attach to insulin receptors on the cells to open glucose channels that allow glucose to go into the cells. When there is abnormal increase of insulin released, that forces more glucose into the cells of your body and reduces the amount of glucose in your blood. That reduction of blood glucose due to the abnormal increased insulin release due to consuming food by definition is reactive hypoglycemia. Underlying issues that cause the abnormal increase insulin release deals with blood sugar regulation, in that it is the hypothalamus, liver, pancreas, and/or adrenal glands that are dysfunctional.
Hyper-parasympathetic Response
The other possibility of drowsiness after that Thanksgiving dinner is what I like to call a hyper-parasympathetic response. To explain what I mean by that, I have to explain generally the nervous system. Your nervous system is broken into two divisions, which are your somatic nervous system (consciously controlled) and autonomic nervous system (unconsciously controlled). Two subdivisions of the autonomic nervous system are your sympathetic nervous system (responsible for the fight or flight response) and your parasympathetic nervous system (responsible for the rest and digest response).
The parasympathetic nervous system when working properly is responsible for distributing blood to your internal organ to allow you to digest and absorb food properly. The nerve that controls the majority of the digestive system (everything up to the distal colon) is the Vagus nerve. As far as the mechanism that causes drowsiness after Thanksgiving dinner, when you overconsume food you are filling your stomach more than usual and activating the stretch receptors of the Vagus nerve more than usual. The increased activation of the Vagus nerve loops back into your brainstem and tells your body to increase blood flow to your digestive organs to accommodate for the extra food, which neurologically puts you into a more restful state.
Since it is the holidays, people tend to indulge in foods that they normally don’t eat on a regular basis, and that is totally fine. The key is to avoid overindulging, because unfortunately that will set you back if you have any weight goals. The most important thing about Thanksgiving is being thankful for what you have, including your health. If your health is not where you want it to be, contact us at Functional Wellness and Chiropractic Center to see how we can help!
Resources
Berthoud HR. The vagus nerve, food intake and obesity. Regul Pept. 2008 Aug 7; 149(1-3): 15-25. https://www.ncbi.nlm.nih.gov/pubmed/18482776
Dugovic C. Role of serotonin in sleep mechanisms. Rev Neurol (Paris). 2001 Nov; 157(11 Pt 2): S16-19.
Kahn CR. The molecular mechanism of insulin action. Annu Rev Med. 1985; 36: 429-451.
Karam JH. Reactive hypoglycemia-mechanisms and management. Calif Med. 1971 May; 114(5): 64-70.
Kamal. 2017. Melatonin. Examine.com. [accessed 2017 Nov 20]. http://examine.com/supplements/Melatonin/
Portas CM, Bjorvatn B, and Ursin R. Serotonin and the sleep/wake cycle: special emphasis on microdialysis studies. Prog Neurobiol. 2000 Jan; 60(1): 13-35. https://www.ncbi.nlm.nih.gov/pubmed/10622375
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