I don't know if this is a similar situation, but years ago I was taking St. John's wort and it tended to flatten out my emotions in a disturbing way. I eventually gave it up because it felt better to have the highs and lows of emotion rather than to have everything the same.
_________________
Never let the weeds get higher than the garden,
Always keep a sapphire in your mind.
(Tom Waits "Get Behind the Mule")