Doctor?s Best 5-HTP (5-hydroxy L-tryptophan) contains a naturally occurring metabolite of the amino acid tryptophan. 5-HTP is extracted from the seeds of the Gri_onia simplicifolia plant. 5-HTP is converted in the brain to serotonin a neurotransmitter substance found at the junctions (synapses) between neurons. It produces a calming and relaxing effect providing support to help maintain mental emotional well-being and to promote healthy sleep.* Doctor?s Best 5-HTP is tested to ensure that it does not contain Peak X.?* At Doctor?s Best we lead with science. Our products are backed by research and crafted using pure ingredients carefully sourced from around the globe. Since 1990 we have dedicated ourselves to providing highly effective nutritional supplements that enable you to live a healthier lifestyle. We want nothing more than to see you and your family thrive!