5-Hydroxytryptophan (5-HTP) is an amino acid that is the intermediate step between tryptophan & the important brain chemical Serotonin. Serotonin is involved in mood, behaviour, appetite, & sleep & is found in many places in the body particularly the brain, gastrointestinal system, & blood cells. There is a massive amount of evidence that suggests that low Serotonin levels are a common consequence of modern living. The lifestyle & dietary practices of many people living in this stress-filled era results in lowered levels of Serotonin within the brain. As a result, many people are overweight, crave sugar & other carbohydrates, experience bouts of depression, get frequent headaches, & have vague muscle aches & pain. All of these maladies are correctable by raising brain Serotonin levels.