I don't know all the specifics, but given all that your phone is connected to I'm sure it gives off some sort of radiation, so I'm sure you'd be safer if you kept if farther away from your head.
I think there’s a certain amount of radiation, though it should be pretty small and within the regulations. But still Better to play it safe as u won’t know about the accumulated effects in the long run!
I do think that mobile devices give off very minute amounts of radiation, but I don't think it's enough to cause any amount of serious harm to you. Though I wouldn't recommend holding a Note 4 next to your head.
Everything produces radiation, but if you don't feel comfortable with your phone being that near you, you can probably charge it further away from you as you sleep.