Every holiday season, we hear the same, old music and people tell the same, old jokes. Every year, after the plastic jack-o-lanterns have been pulled from store shelves and replaced with shiny, aluminum tinsel in every color, someone inevitably makes a wisecrack about the dangers of consuming turkey; "I hope you're not planning to drive after eating all that turkey!" Hardy-har. The problem with these silly remarks is that few people actually take the time to learn about tryptophan and its sleep-encouraging ways.
What is tryptophan?
Tryptophan is an amino acid famously found in turkey. In fact, it is also found in chicken and pork. The body metabolizes tryptophan and eventually turns it into a well-studied neurotransmitter called serotonin. Serotonin is known to induce a calming effect after its release in the brain, and is thought to help regulate sleep in the human body.
Great. So does it make you sleepy?
Technically, yes. The ingestion of even a small amount of tryptophan can be enough to put a person to sleep, however, for this to work, the tryptophan must be taken in on an empty stomach. Chances are, in addition to that bear-sized portion of turkey, you're eating several other foods creating an environment in which your stomach is not empty. Not to mention the fact that there are other things in the turkey such as protein, some carbohydrates, and several other amino acids whose synthesis in the body help to counteract the effects of the tryptophan.
Well if it's not the tryptophan in my turkey, then what?
The average Thanksgiving meal contains somewhere in the ballpark of 3,000 calories. Aside from the turkey, common Thanksgiving foods include mashed potatoes, bread, corn-on-the-cob, yams, alcohol, and of course, pumpkin pie. All of these foods are certainly tasty and festive, but they are also chock full of carbohydrates and fat. It takes more energy for the human body to digest fats than it does to digest other types of food, and it also takes more energy to digest large amounts of food. The combination of the large meal and the approximately 200 grams of fat require the body to reroute a large portion of its energy and bloodflow to the digestive system where it will spend the next several hours breaking down the meal. This is enough to make anyone sleepy, but if you couple it with the fact that the other amino acids which generally counteract the effects of tryptophan are also leaving the blood to aid in digestion, thus leaving an increased relative amount of serotonin production, you have the perfect recipe for fatigue. And, of course, alcohol is a natural central nervous system depressant. Drinking it with your Thanksgiving meal will certainly contribute to your desire to nap.
