Turkey and Tryptophan: Thanksgiving Myth Debunked
ƵƵƶƶ Why do we feel sleepy after a big meal? You’ve probably blamed the Thanksgiving turkey for having too much tryptophan, an amino acid that the body converts to serotonin and melatonin, two sleep-inducing compounds. But it turns out that tryptophan has to be consumed on an empty stomach and not with gourmandish excess of cranberry sauce and pumpkin pie, to be effectively blamed for your soporific state. Did you know that even oat bran and soybeans contain more tryptophan than turkey? Check out this infographic ▶ http://goo.gl/pQtLTp .
ƵƵƶƶ Another popular theory is that after a big meal, our body diverts blood supply to the gut, and away from the brain, to help digestion. While this seems logical, it turns out that cerebral blood flow and oxygenation are kept stable through autoregulation mechanisms even when blood flow to the gut or muscles increase after a meal or during exercise. Blood vessels in the brain expand or contract in response to changes in blood pressure to keep flow constant. Another myth debunked!
ƵƵƶƶ The most likely culprits are gut-brain hormones that regulate both feeding and sleep. Orexin is one such example: it promotes hunger and alertness, but is inhibited by gastric distention and satiety. The ability of hunger to promote alertness is thought to be an evolutionary adaptation that keeps us motivated to search for food. Interestingly, mutations in orexin were recently linked to narcolepsy, a pathological form of sleepiness. Finally, it has been argued that sleep allows for “cognitive reinforcement” of the circumstances that led to your energy acquisition, an important survival skill! So when postprandial somnolence hits you after your big Thanksgiving meal, you’re actually learning an age-old survival mechanism 🙂