When you are asleep, your mind is at its true potential, in full conscious awareness, contemplating higher thoughts and imagining the truth of the universe. While you are ‘awake’ you stumble through life hardly aware of anything but your immediate surroundings, and your ‘sleeping’ self has no time for this you, only even thinking about it if you fail to eat enough, or get injured.
If aliens visited this world, they would only want to talk to humans while they were asleep, since this is when their minds are truly awake.
Jonas David 