Hi, my son who's 26 was having a wellness check (for insurance) and when she was taking his blood pressure reading, he started going blank, she couldn't get any reading and he was just staring ahead upright in his chair, his eyes were large, open and dilated, but he was unresponsive when we tried to talk to him and give him a glass of water, we got him on the floor to lay down and he was totally wet from sweating. He soon came too and began to feel better within just a few minutes