5-HTP, also known as 5-hydroxytryptophan, is the direct precursor to the neurotransmitter serotonin. Low levels of serotonin are associated with sleep problems, despair, abnormal apprehension fearfulness and compulsive eating, malfunction of mind or body, restless leg syndrome, migraines, fibromyalgia and low discomfort threshold. Many people who are afflicted with one of those conditions often have others, which has led some researchers to label them collectively as "Low Serotonin Syndrome. Serotonin is an important initiator of sleep. In numerous studies 5-HTP has been shown to decrease the time to go to sleep, decrease the number of awakening hours. It also increases REM sleep and deep sleep. http://www.herbsmd.com/detail/5-htp-plus-30078.htm