http://articles.mercola.com/sites/articles/archive/2008/01/02/tryptophan-part-two.aspxPatients with seasonal affective disorder who had responded to a standard regimen of daily 10,000-lux light therapy were given a tryptophan-free amino acid beverage plus amino acid capsules was used to deplete tryptophan. The beneficial effects of lightenCommunityServer 2008.5 SP1 (Build: 31106.3070)