i believe that the sand would attempt to help him in either case. from what we know, it protects gaara regardless of his will. also, the sand was apparently infused with Gaara's mother's desire to protect her son and seems to act according to what her will would be.
also, Yes gaara sleeps. he has slept ever since his first battle with Naruto. after that battle he slept, his personality was stabilized, and he became respected and admired by the village and he even managed to have some control over Shukaku's power as evidenced by his battle with Deidara in which we see gaara freely using the one-tail's arm
@ Icelerate:
i don't think it'd be weaker because he doesn't control it in the first place. it works automatically like when Yashamaru tried to get him from behind when Gaara was just a child who had absolutely no control over anything and it protected him perfectly from yashamaru who was an Anbu-level shinobi