Final answer:
The amino acid in poultry that could make you feel sleepy is tryptophan, as it's a precursor to serotonin, a neurotransmitter associated with relaxation and sleep.
Step-by-step explanation:
The amino acid found in poultry that makes you sleepy is: tryptophan. Amino acids are the building blocks of proteins and each has a distinct R group that determines its unique characteristics. Tryptophan is an essential amino acid, which means it must be obtained through diet since the body cannot synthesize it. This amino acid is a precursor to the neurotransmitter serotonin, which is responsible for feelings of well-being and happiness, and can be a natural sedative, leading to sleepiness after consumption. Serotonin is further converted into melatonin, which helps regulate sleep-wake cycles. So, when you consume foods high in tryptophan like poultry, your body uses it to produce serotonin, potentially increasing feelings of relaxation and drowsiness.