That was me exactly in the later stages of mercury toxicity before my amalgams were removed. I did best at night and hence spent over 12 years on a night schedule... to bed between 4 and 6 am, up between 11 am and 1 pm.

I am currently on a normal schedule for only about the 3rd time in my life... bed at 11pm, up at 6 am. Mercury seriously changes circadian rhythms in many people. I believe this has to do with brain chemistry.