If you have fine, frizzy hair - problem solved! These rollers do the trick! Wash your hair, rough blow dry, put these rollers on for 2 hours and watch your hair transformed without any heat damage! I tried other brands and nothing works as good as these little hair helpers! Extra bonus - they are super light, so you hardly feel them on your head. Regarding sleeping in them- can't say, didnt try it! But honestly, 2 hours in them is truly enough! Great product, great results!