Well above the free laundry, the comfy bed, and the ‘joys’ of younger siblings, Thanksgiving dinner is by far the best part about going home for the holidays. After a solid month and a half of surviving on nothing but cafeteria food and an excessive amount of Tim Hortons, just about any homemade meal would taste fantastic. But turkey and stuffing? Simply heavenly.
It’s an age-old myth that eating turkey makes you sleepy. But wait, you say, I always feel ready to take a nap after two (or three or four) helpings of Thanksgiving dinner. And it’s true. Eating Thanksgiving dinner will make you ready to hit the hay. But it isn’t so much the turkey as the entire carbohydrate-rich meal in general.
The myth goes as follows; eating turkey makes you sleepy, because it contains a lot of tryptophan, the sleep-inducing amino acid. But gram for gram, cheddar cheese has more tryptophan than turkey, and most people don’t fall asleep after eating a cheese sandwich, or a string cheese.
Scene- Afternoon, sun streaming in the windows, Grandfather asleep in a recliner in front of the television.
Granddaughter: Play with me, Grandpa!
Grandmother: Grandfather’s napping, dear. You know how string cheese knocks him out.
Turkey does contain a lot of tryptophan, though, and it is this amino acid that ultimately causes you to feel tired after a big meal. When you eat turkey- or anything else high in tryptophan- the amino acid makes its way through your digestive tract into your blood stream, along with all the other amino acids from your meal.
Tryptophan makes you sleepy because in the brain it forms serotonin, and ultimately, melatonin. Melatonin is the ‘sleep chemical’ in your brain. It makes you feel tired, and allows for a regular sleep schedule. But the tryptophan from the food you just ingested is in your blood- not your brain. And to get to the brain, it has to pass through the blood brain barrier first- the guard that decides what gets into the brain.
Tryptophan is as equally important to the brain as any other amino acid, and since you just ate a huge meal full of amino acids, there is a line-up to get into the brain.
You know what else your huge meal was full of? Carbohydrates.
When you ingest a large amount of carbohydrates, both insulin and glucagon are released into the blood to take care of all the sugar the carbs produced. The insulin allows for the use of the glucose in the blood, and glucagon keeps the blood sugar at a steady level. Both the processes use up many of the amino acids in the blood- but not tryptophan.
Tryptophan now has a clear path to the brain, where it begins making serotonin, and it eventually makes you sleepy.
Really, you could eat a meal full of turkey, but if it had few or no carbs, the tryptophan would have little effect on your brain. Take this knowledge with you to Christmas dinner. Fill your plate with turkey, but if you want to avoid the after dinner nap, skip taking a second helping of that sweet potato casserole.