I'm really sensitive to it. I have a light that I can adjust the intensity and timer and even using it at 15% (I think 50% is normal) and for 5-10 minutes instead of the 15 recommended for that type of light I still have gotten manic from it. We usually make a month to month decision about using it. Some years I do and some years I don't touch it. This year I won't be using it at least until Jan-Feb because I'm too unstable.

It is so good when it works though.....