@ Osmodin You have to know your rem cycle pretty well for it to work, It didn't work last night for me, but then I slept through it, which is another good thing. If your not close to rem, it's not strong enough of a vibration and the noise factor is now all but gone so it won't wake you out of deep sleep. I set Like 3 last night 4 6 7 hours apart and missed them all, I won't lie this is not foolproof, but it seems really good.