I find that the state you enter in a WILD WBTB still counts as refreshing sleep. Try to bring your mind to an aware state quickly, say five minutes. It seems to me that the time you are up is the only big interuption in your sleep. If you are doing it correctly you are actually asleep during most of the attempt, just aware.
A yogi trick I used to play with is getting needed rest in a meditative state, but not actually loosing awareness at any point. I am not claiming I could sustain that beyond a couple days, but you should be getting rest even during a WBTB attempt. I often even attempt four or more times in a night, and still feel well rested.