Based firmly in first person experience with now more then half a dozen people I have dealt with. I discovered that on line when I was researching manic depression. I found two research doctors who had found that "The only effective treatment for Depression is sunshine- vitamin D." I get someone started on D3 supplements or, in Việt Nam, being outside under that subtropical sun un short sleeves. The results are obvious immediately for someone who is in depression and for others whose depression is episodic or what used to be called "manic depression" the results are obvious when they go a long time without being depressed.
Look it up yourself, it's easy, unless you want to continue to believe that only prescription medications could possibly be useful.