Ground turkey

I know there's less fat in ground turkey then in ground beef but for some reason, ground turkey knocks me out after I eat it and I can't figure out why. Scientists proved that tryptophan doesn't make you sleepy it's the blood that rushes to your lower intestine but this is more then sleepy. I eat and I cannot stay awake a half hr later. Sometimes I don't remember falling asleep! I know I have the option to not eat it but I'm curious to if anyone else goes through this or knows why it's happening. I tries to Google it but the results are only telling me that tryptophan is a myth. Please help?