Our body is designed to regulate and balance itself, tryptophan is the amino acid that is needed to synthesize serotonin and melatonin. We need serotonin to be energized and motivated during the day and melatonin to sleep and regenerate at night.

Your body will only make as much serotonin/melatonin as it needs, so taking extra tryptophan is a relatively safe alternative remedy for people seeking help with depression. Decades ago it was used widely for that purpose, then a tainted batch of it appeared leading the FDA to suppress its availability just at the time Prozac was being marketed.

Prozac was the first SSRI and it "works" by disabling the reuptake of serotonin to temporarily cause serotonin levels in the nervous system to elevate. That can lead to excess serotonin (too much stimulation and manic behavior) as well as to the body adapting by reducing its serotonin receptors to prevent the excess, but with the reduction in receptors when you try to stop taking the SSRIs then there won't be enough serotonin getting into the system and the depression can be worse than it was before starting the medication.

There wasn't a problem with people using tryptophan supplements (or eating foods high in tryptophan) committing homicides and suicides, but there definitely has been a problem with the SSRI drugs triggered those outcomes.

: https://youtu.be/_B1gcPprK3c

: https://youtu.be/ycTWLHgtq94