Kendrick wonders if his aspirations are the cause of his fixation with death. He also creates a metaphor playing off the connection sleep, dreaming and death have with one another
He’s saying he’s idealistic like John Lennon (“You may say I’m a dreamer…” from “Imagine”) and that this could lead to his downfall.
A reference to the 1994 Nas track “NY State of Mind.” Kendrick is playing with danger “being a dreamer”, sleep being the cousin of death.
http://www.youtube.com/watch?v=UKjj4hk0pV4
Also, that Nas is part of our favorites that would probably vouch.