Spatial disorientation, loss of awareness which way is up, down and left and right, occurs very quickly when you loose visual refences to the horizon. As soon as that happens you need to be using the flight instruments for flying, transition immediately to them, and know where your at, what altitude and direction in degrees on the compass you need to continue flying safely.
It doesn't take but a tic toc to get honk up bad in fog or clouds, I've seen the same thing happen at night when flying away from a well lit urban area into a dark undeveloped area in SO CA and AZ.
Flying is not for everyone and it is not easy to do well under bad conditions