I'm Going In For A Colonoscopy At 7 Am. Tomorrow

I'm going in for a colonoscopy at 7 am. tomorrow morning. I'm male, 66 years old. I took milk of magnesia last night, and have had 20 mg of Dulcolax since noon. (I'm do to have anther 10 mg in twenty minutes. I'm feeling a bit dizzy, not just because I'm hungry. I've taken 32 oz. of Gatorade so far since noon, and am instructed to take 3 capfuls of Miralax with 8 oz of Gatorade every 30 minutes at 6:30 pm., 7:00 pm. and 7:30 pm. Could any of these things be creating my dizziness?