Have you ever imagined waking up as someone or something other than yourself? what would that feel like? what benefits and challenges would you instantly experience?

Yeah! 
Fort this question, you would need to think deeply and reflect on yourself but if it were me this are the answers:
It would feel unnatural like you possessed some being apart from yours. Your mind would try to process and try to play the role of whoever or what you imagined.
The benefit is the feeling of achievement like an alarming state where you are someone else. The instant challenge is to bring a  sense of control in your current state