Yes, 5 HydoxyTryptoPhan is the precursor to serotonin in the brain. It is the last stage that can still cross the blood-brain barrier. Since serotonin is used elsewhere in the body, the brain creates a "barrier" to help essential chemical levels in the brain to not be affected by the rest of the body.
I've taken 5HTP for 4-5 years. It tends to brighten the mind. That being said, it can be dangerous if used in a bi-polar individual. It could cause a manic swing to take place.
I use it to treat depression, there are also other supplements/treatments in the depression area that can also make a significant difference. Let's chat.