I purchase this for my daughter go off to college . she have never be able to wake up to a `` normal '' alarm clock . she be a extremely heavy sleeper but the shaker and incredibly loud alarm always wake she up . I do not think she be ever late to class . she even have friend order they once they hear hers . she take it overseas with she , plug it in and `` fry '' it due to the different wattage . I immediately purchase another one when she return to the US . one of the best `` off to college '' purchase we make !