Why do holiday meals make me sleepy?

by Nick Rose, M.S., PCC Nutrition Educator

This article was originally published in November 2011


Have you ever noticed how everyone wants to take a nap after the big Thanksgiving meal? Ever wondered if it is something in the food? Many people believe that the nap-inducing powers of Thanksgiving dinner are a direct result of the essential amino acid tryptophan in the turkey.

Turkey definitely is one of the best dietary sources of tryptophan. But tryptophan also is found in other meats (chicken, beef, lamb); seafood (tuna, salmon, shrimp); and some seeds (pumpkin, sesame). Some tryptophan is used by the body to synthesize the vitamin niacin. The rest travels to the brain, where it’s converted into the neurotransmitter serotonin and then into melatonin (which makes us sleepy).

This reaction can help relieve symptoms of insomnia, mild depression and other mood disorders. Tryptophan is available as a dietary supplement at PCC to help treat a variety of sleep and stress-related conditions.

But back to Thanksgiving. Eating a large meal causes our blood sugar (and therefore our insulin) to peak at levels they don’t normally reach. The elevated blood levels of insulin and tryptophan following the traditional Thanksgiving feast create the “perfect nutritional storm” for a good siesta. The insulin drives most amino acids (but not tryptophan) into muscle cells, increasing the ratio of tryptophan to other amino acids in the circulation. The tryptophan then can flow right across the blood-brain barrier, where it will be converted into serotonin. Sweet dreams.

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