NOV 23, 2016 7:06 AM PST

What's Really to Blame for Post-Turkey Napping

It’s almost time to belly up to the table and start wolfing down a huge meal. It’s part of a Thanksgiving tradition to cook and eat mass quantities of turkey, stuffing mashed potatoes and gravy. While the holiday is supposed to be a re-creation of the feast shared by the Pilgrims and Native Americans, that’s pretty much a myth. There were no big groups of Native Americans breaking bread with the English and a large feast at that point in history would have included venison, duck and pheasant and likely no stuffing or potatoes.
  
The struggle to stay awake after a big meal is real however, even if the reasons behind it are not are not always presented accurately by the media and, of course, know-it-all relatives at the table. The most common myth is that turkey contains an amino acid called L-tryptophan and it’s this ingredient that makes people sleepy after a meal. There’s more science involved in the process though. L-tryptophan is an essential amino acid; we need it to make a B vitamin, niacin, that keeps skin and muscles healthy. We also need it to produce serotonin in the brain and serotonin then produces melatonin, which makes us sleepy. It all starts with L-tryptophan, but there’s more to it. The human body cannot produce this amino acid it so our diet has to include it.
 
 It’s not just found in turkey however, it’s in other foods like yogurt, fish and eggs. In fact, chicken has more of it than turkey does. While many blame turkey and it’s tryptophan for higher serotonin levels, the fact is that L-tryptophan cannot act alone on the brain, because it cannot get through the blood brain barrier. It needs carbohydrates for that. The kind found in stuffing, mashed potatoes and those delicious desserts.  Without the carbs, L-tryptophan would have nowhere to go. To say “turkey makes you tired” isn’t scientifically complete.
 
But we do get tired after a big meal, and not just at the holidays. It’s called post-prandial somnolence and it happens not in the gut, but in the brain.  The carbs needed to bind L-tryptophan cause a rise in insulin, which pushes proteins out of the blood stream and into cells to turn food into energy. With less protein in the blood, L-tryptophan can bind easier to the remaining proteins and slip through the blood brain barrier and to do its thing. 
 
The nervous system is involved too, way more than the stomach. The autonomic nervous system controls how the organs in the body work. The heart pumps, the lungs breathe, the stomach digests and all of that is controlled by the autonomic nervous system. After a large meal, of any kind, the autonomic nervous system interacts with the sympathetic and parasympathetic nervous systems and this shift makes us less aware of our surroundings, less able to concentrate and results in the lethargy that we call a food coma.  This sleepiness can last for a bit too, since the serotonin and melatonin produced by tryptophan gets stored in the brain. Basically, after you eat that big Thanksgiving meal, don’t make any plans that involve being too far away from a couch.
 
Check out this video on how it all works and have a Happy Thanksgiving and a pleasant postprandial somnolence.
 

Sources: Food Republic Miami Herald ScienceAlert, Scripps
About the Author
  • I'm a writer living in the Boston area. My interests include cancer research, cardiology and neuroscience. I want to be part of using the Internet and social media to educate professionals and patients in a collaborative environment.
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