Can you lie on your side ALL night? Can you lie on one arm all night? Those are the instructions. I ended up keeping my arm at my side but then my head eventually falls off the end of the pillow. Yes, this pillow does prevent you from rolling over onto your back but it ALLOWS you to roll OFF the pillow. I use it to fall asleep but I inevitably find myself sleeping most of the night on a standard pillow. I recommend trying to stick with your CPAP or APAP even tho I quit using the machine too. I'll keep looking for other options.