I totally agree with kimbellgirl Sleep will make all the difference in the world. When I was only sleeping 3-4 hrs at nite then napping on and off all day, I was completely spaced out all of the time. Now I can definately function much better. The magnesium citrate will help with sleep but also lowers BP, so if you have low BP, be careful. Otherwise, Magnesium is wonderful for so many things. I too had sleep apnea prior to my POTS dx. Had a UP3 ( tonsillectomy, uvula removed and pallot shaved) and no more sleep apnea for me. I believe, as do my dr's that the sleep apnea was due to my large tonsils. I do not snore at all now Definately worth having a sleep study liz