I really despise supplements that mess with my sleep. There are a few which don't effect me negatively in the daytime, but when I wake up in the middle of the night they make it nearly impossible to fall back asleep. The ones that I found do that for me are high-doses of iodine, methylcobalamin, betaine, milk thistle, turmeric (curcumin), and probably a few that I'm forgetting.

So it could be something you are supplementing with causing this problem, or at least exacerbating it. Do you normally, while not chelating, sleep through the whole night without a problem?