Turkey makes some people tired after they eat it because the turkey contains amino acid which are the building blocks of proteins.
Those proteins from the amino acid make some people tired after eating it.
My brother gets tired after eating turkey but I don't so it can depend on the person as some people get tired after eating turkey and other people do not.
The amino acid in turkey that makes some people tired is called tryptophan, which forms the basis of brain chemicals that make people tired.
Different peoples brain and body reacts differently to those chemicals so yes turkey can make some people tired after eating it while other people may not get tired.
It's normal either way.