It would be lucid dreaming if he went deeper, but if he's still just seeing just black he's not deep enough into it for the dreaming to start. Next come color blobs, then sounds, then flashes of imagery and eventually full on 3d as if you're there dreaming. It's wicked to maintain consciousness without blacking out from the waking state into the dream state.
http://www.messagefrommasters.com/Meditation/Meditation_Tech...