SUDOKU!
Omg I love sudoku <333 But it gets terribly addictive. I know exactly what you mean about the sleep thing. It just dominates all thought and keeps going on and on and on...

So yes , in short I'm a fan of puzzles. I especially love it when I compete with friends to finish one or something (I have an extremely competitive nature inside of me XD). Crosswords, Sudoku, word searches... I love them all ^^.