Does chronic emotional stress actually deplete serotonin levels in the brain? or is that a myth?

Myths - a basis bit: Like most or all myths, there is a bit of a base. It's not at all like stress causes you to 'use up' serotonin. It's that there may be a type of person (nature+nurture) who has lower levels to begin w/ and thus tends to have more difficult stressed lives. Diet is a way to levels a bit and avoiding alcohol, caffiene or nicotine may help. See how you react. CBT or meditation are ideas too.