Mercury interferes with T3 (thyroid hormone) production as well as iodine utilization. This could explain why you felt tired so often. I experienced that same thing:

My Mercury Story

I also suffered ADD-type symptoms when mercury toxic. Of course, I didn't realize that until a few years after my amalgam removal when I was actually able to concentrate and understand what I was reading without finding my mind drifting 2 to 3 times per paragraph.

The difference now is amazing.

I hope this helps.