I don't understand how they lose control from using their visuals, to their instruments!
It can happen all too easily. I found myself in such a situation, where I had zero external visual references and was forced to rely solely on my instruments. Long story short, the instruments were telling me one thing, and my body was telling me something else altogether. I had been switching my view from the instruments to outside the aircraft, looking for some kind of reference, and back.....and looked outside the aircraft for a couple of seconds too long. Once I was able to see outside again, it was like a jolt through my body as it synched itself to what the aircraft was actually doing.