I have often heard people mention that they get sleepy after eating a large turkey dinner.   Is this related to the amino acid, named tryptophan, which helps people sleep?

Dr. Lawrence Steinman, MD, a neuroimmunologist at Stanford Medicine, indicates that tryptophan in our food is converted to serotonin and melatonin in the brain and may help you sleep.   Check the link: http://scopeblog.stanford.edu/2011/11/23/fact-or-fiction-talkin-turkey-and-tryptophan/

The uptake of tryptophan and its conversion to the aforementioned compounds take several hours.  Since the body cannot make tryptophan, one has to consume foods that contain adequate tryptophan in order elevate blood levels.  Turkey does not contain any more tryptophan than typically seen in other meats.

Dr Steinman suggests that the reason people often get sleepy after a large turkey meal is more related to massive ingestion of calories from all the food as well as any potential influence of any alcohol that may have been consumed.

Essentially, eating turkey does not make you sleepy.  This is more of an urban legend than an actual fact.