Speaking of mathematicians and dreams, I found a hilarious quote some time ago:

"Once in my life I had a mathematical dream which proved correct. I was twenty years old. I thought, my God, this is wonderful, I won't have to work, it will all come in dreams! But it never happened again."

--Stanislaw Ulam; January 14, 1974, in "Conversations with Gian-Carlo Rota"; as quoted on pg262 of Turing's Cathedral (2012) by George Dyson