If I do too much mentally or physically or even just stay upright too long a predictable scenario happens. Go to bed, stomach churns,muscles twitch, heart races, sometimes sweating and if I manage to drop off through all this I will have horrid adrenaline filled nightmares. I think it is due to orthostatic intolerance as it happens on those days when my blood pressure has been low and pulse high on standing. I even checked my blood sugars which are consistently normal as I fear going diabetic as I had large babies,( a risk factor). Does anyone else get these episodes at night and any ideas how to reduce them, as it feels like adrenaline overload to me which I think may be due to the body pumping it out to get the blood round all day when I am upright. I tend to sit up and drink water when it happens and wait for it to get less. Anyone else have this and do you think it is due to POTS?