I am notorious for being a deep sleeper (Ive slept through a fire alarm once or twice) and this app is fantastic. You have to leave it open for it to work, which is a slight annoyance, but its worked for me for months. Its just annoying enough to coax me out of a deep sleep, but not annoying enough to where I just shut it off (a problem Ive had with many alarm apps). I still have to set basic alarms to follow it, but so far my current employer and I appreciate this app immensely.