There are a few different types of healings and cleansings I've experienced during meditation. Some involve waves or vibrations passing up over my whole body. Some involve trickling or shimmering sensations coming from one spot and disappearing upwards. My favourite, though, would probably be when my spinal column gets a good clean. This involves feeling open at both my crown and base of spine simultaneously. Then it feels like gunk is drawn up along my column as if by a big syringe. It tingles and feels great. I'm not sure why different types of cleaning happen at different times. It all seems to be organised by processes which are outside my awareness.