Every Thanksgiving, myths of the quasi-magical powers of tryptophan rise again.

There’s the turkey/drowsiness myth: Eating lots of juicy turkey meat supposedly makes people feel tired because it contains an amino acid called tryptophan. This molecule travels into the brain, where it’s converted into a neurotransmitter called serotonin, which in turn is converted into a hormone called melatonin. Voila! Sleepiness.

But science and the internet agree: It’s not the turkey’s tryptophan to blame for your post-feast nap. All protein sources, and even vegetables, contain some tryptophan; turkey isn’t at all special in this regard.

What could eating more tryptophan, or taking it in pill form, mean for your brain? <a href="https://www.shutterstock.com/image-photo/5htp-bottle-l5hydroxytryptophan-precursor-serotonin-1052268893?src=9701ca16-33c4-4a4d-91d7-f45bafa7eed1-1-0" rel="nofollow noopener" target="_blank">Evan Lorne/Shutterstock.com</a>