Valerie, I too woke up in the middle of the night on my second cleanse with wierd heart feelings...not really scarey, but unsettling. The third flush I used half the amount of Epsom Salts , same amount of water, less salts, and I didn't have the problem. It didn't seem to interfere with the flush results either.
I do drink lots of apple juice and have no food the day of the flush, so I get pretty well cleaned out anyway.