It seems as though part of the annual Thanksgiving Day tradition is the post-meal snooze, wherein everybody first partakes of the feast, then finds a cozy corner in which to curl up and snooze until they feel as though they can rebutton the top button of their pants. Some people refer to this phenomenon as going into a food coma, but the truth is that there are only some foods that will do this to you … and despite a common myth to the contrary, it’s not all about the turkey.
People generally point to the turkey as the root of all of that sleepiness, saying that it is one of the foods highest in its levels of a sleep-inducing chemical known as tryptophan. Though it’s true that turkey contains the stuff, it is not at all true that it is highest. In fact, you ingest the same amount of tryptophan when you eat turkey that you do when you have roast chicken, spare ribs, or a steak. Eat a vegetarian meal that contains freeze-dried tofu and you’ll likely take in twice as much tryptophan! So what’s the reason that every third Thursday of November leaves us all feeling so somnolent?
It’s less about the turkey than it is about the turkey in combination with all of the other foods that have come to be the traditional Thanksgiving fare. On a normal evening we eat our tryptophan in a regular portion, and combine it with green vegetables and a small amount of carbs. But on thanksgiving we are throwing in alarming quantities of mashed potatoes, sweet potatoes, stuffing and pie – all of these overburden our systems with the sugar known as glucose, and that means that our body has to work overtime to regulate all that overload. It does that by releasing insulin.
What does all that insulin do? It recruits other amino acids in the body to help it get rid of the sugar, and when it does that it leaves the tryptophan in the turkey with a lot more access to the brain than it would normally have if all the other amino acids weren’t being recruited away for other jobs. With the undivided attention of the brain, the tryptophan is free to get converted into serotonin in higher concentrations than it would normally, and that is what makes us get so drowsy.
So is it just the combination of turkey and carbs that do the trick? If so, does that mean that anytime we’re having trouble falling asleep we should just have a meal of mashed potatoes and tofu or steak in order to get the eight hours of snoozing that we need? Unfortunately not. A big part of the impact is that we have eaten so much that it triggers our parasympathetic nervous system and makes the body work overtime to rest and digest. And of course, there’s also the impact of travel, the emotional impact of seeing family and friends, the work of preparing the meal, and maybe even being outside for a game of football or watching a parade.