5-HTP supports the production of serotonin in the brain and central nervous system; serotonin can impact sleep, mood, appetite, and body temperature. 5-HTP therefore, is typically used as a sleeping supplement because it supports the production of serotonin, which is in turn, converted to melatonin. Melatonin is a neurotransmitter that helps to regulate healthy sleep/wake cycles. Studies have shown that taking a dietary supplement containing 5-HTP can help people feel more rested upon waking up and can give people an increased energy level during the following days.