Just a reminder to everyone that it is really important to be aware of Serotonin Syndrome, which is when spiking serotonin levels can make one dangerously, even fatally, ill.
Serotonin IS essential for many aspects of health, and some people benefit from the supplements that increase it(eg tryptophan, 5-HTP, Inositol, St John's Wort etc), or from certain rx meds that do so, and are specifically prescribed --- but one should never take more than recommended, and also NEVER combine supplements or medications or medications and supplements that raise serotonin levels.
More info on Serotonin Syndrome from Mayo Clinic (there are many other reputable sources of info as well)
Serotonin syndrome - Symptoms and causes - Mayo Clinic