Tryptophan is the rarest of the essential amino acids found in food and is the precursor of serotonin.
Serotonin (aka the “happy hormone”) is important for providing a feeling of calm and well-being
This is why tryptophan is often prescribed
to induce restful sleep
A deficiency of serotonin can result in or affect:
depression,
anxiety,
insomnia,
excessive anger
mood swings
alertness,
ability to concentrate
pain sensitivity.