It's normal to nod off when you're on pain pills or any opiate for that matter. But why would you wanna go to sleep? Just lay down and enjoy the high...you'll think you're going to sleep, but you'll just be noddin' off. Feel the euphoric buzz and let it take you to different places. But yeah, to answer you question, it's safe for you to fall asleep, if that's what you wanna do.