Instruct: Classify Amazon reviews into positive or negative sentiment
Query: One of my best purchases ever

I have narcolepsy, and getting up in the morning is challenging, to say the least. I routinely set three alarm clocks, including this one. I have the vibrator set only--no sound. Pretty consistently, this is the one that I get up to, after sleeping through one or two before. It's been a real lifesaver, and I've recommended it to other people with narcolepsy that I know. I keep the vibrating disk between my mattress and box spring, so the vibration is pretty gentle, but still effective enough. I've even slept through my super-loud, annoying clocky, but the vibration from this clock gets me up every morning. Great product!