L-Tyrosine is a free-form amino acid which rapidly crosses the blood-brain barrier.
...These Source Naturals supplements utilize the powers of L-Tryptophan, an amino acid used in multiple areas throughout our body, along with the essential Vitamin B6. L-tryptophan plays a crucial role in the production of both melatonin & serotonin. Melatonin is produced by the body to help induce restfulness & sleep as darkness increases.