What is the role of the amino acid with the one-letter code W in the body, specifically in relation to its potential effects on sleep and mood due to its presence in foods like turkey?

The amino acid with the one-letter code W, which is tryptophan, plays a role in the body by being a precursor to serotonin, a neurotransmitter that affects mood and sleep. When consumed in foods like turkey, tryptophan can potentially increase serotonin levels, leading to improved mood and sleep.