Try to describe what he was seeing in this dream like state was like trying to explain why the Earth was round or why Sherlock had an obsession with doing experiments on the kitchen table. It was strange and he was constantly being pulled out of what he believed to be wakefulness into a deep and never ending darkness only to find himself back into the fake wakefulness.
The dreams would always amplify the pain and numbness that would flood John's body, making him believe that he was awake until the always welcomed darkness forcefully returned.
He could handle the darkness. It was peaceful and relaxing and he didn't feel the dead weight of his body as it just lay there. In this state he could hear what was happening around his physical form.
He could hear the nurses as they checked his vitals, he could hear Mrs Hudson as she clucked over the silent Sherlock.
He could hear the deafening silence that surrounded the room whenever Mycroft would visit, sending a silent threat to John that somehow Mycroft would bring him back to life if John died and kill him in ways that John couldn't even imagine.
All the while he could hear Sherlock's voice talking to him and drawing him into the world of the living like a beacon.