I agree with BB here. If your UF's are high, you may be dehydrating yourself during treatment and that will cause your BP to drop like a rock. I've only had one scary episode since I started with this wonderful process of dialysis,
and that was a day when I drew off a lot of fluid, didn't drink much and ate even less. I woke up on the floor of the bathroom heaving my guts out. It was the only time I ever let that happen. Try keeping your fluid levels up and see if that helps you with your BP and likely the lightheadednes. Good luck!