Sleep problems?

Just wondering if anyone can give me some advice. I have been sleeping really badly since the end of January. I just lie there for hours, tossing and turning and worrying. I eventually get to sleep, only to wake up at between 3am and 4am and find it almost impossible to get back to sleep again. My doctor has now given me sleeping tablets but they don't seem to be working.

I'm just not sure what's causing all this. I was told to take a leave of absence from work at that time, which has caused me a lot of stress and anxiety. But it was also at that time when I started using a lightbox. Is it possible that the light box is causing the sleeping problems? I read all the info, I use it for an hour when I get up and I initially used it for half an hour after lunch, I increased this to an hour after a week as it wasn't having any effect. I've been tracking my symptoms on the lumie questionnaire and I got worse - although this was probably caused by the fact that I was told I couldn't work.

To make things even more complicated I have ongoing problems with depression throughout the year as well as SAD. I also have very severe anxiety. I take 2 kinds of antidepressants, 2 kinds of antianxiety tables and I also take omega 2, multivitamins, echinecia and vitamin b supplements as I've been told all of those things are good for dperession, anxiety or SAD.

Is there anything else I can do?