By Kim Smiley

Every year around this time, Americans start thinking about turkey and that sleepy feeling that hits after a Thanksgiving feast.  It has been common to blame the bird for the post feast drowsiness, but is the idea that turkey causes sleepiness true?

This issue, just like any big engineering problem, can be analyzed by building a Cause Map.  A Cause Map is an intuitive, visual format for performing a root cause analysis.  To build a Cause Map, “why” questions are asked to understand the cause-and-effect relationships between the different causes that contribute to an issue.  One cause in this example is the  fact that turkey is typically eaten at a tradition American Thanksgiving feast.  The rumor that it causes sleepiness likely came from the fact that turkey contains tryptophan, an essential amino acid that is found in protein.  Tryptophan is a natural sedative because it used to help the body produce the B-vitamin niacin, which in turn is used to make serotonin.  The body then uses serotonin to make melatonin which helps regulate sleep cycles.  Higher melatonin levels can make a person feel sleepier.

If you stopped the investigation at this point, it might look like turkey is in fact responsible for that post-Thanksgiving nap, but there is more to the story.  The first important thing to note is that turkey doesn’t really contain that much tryptophan compared to other foods.  Turkey actually has less than chicken, which Americans regularly consume without the need for a nap.  Tryptophan is also much more potent when eaten on an empty stomach, which is probably not the case on Thanksgiving Day.

The conclusion is that you can’t blame the bird.  It’s a myth that turkey causes more sleepiness than other foods.  If you feel sleepy after feasting for Thanksgiving it probably has more to do with the work to prepare the meal and amount of food consumed than the properties of the turkey.  But please don’t let this conclusion ruin your fun; feel free to nap the afternoon away anyway.

Happy Thanksgiving from ThinkReliability.  We hope you have many things to be thankful for this year.