Ive used this app for years now on a variety of laptops and its never let me down. It is simple and works just like a traditional physical alarm clock. Like many other reviewers have pointed out, it has an awesome setting to change your system volume during an alarm. So even if you accidentally leave your volume muted at night, you can still hear a full-blast alarm in the morning. I have not used the additional helper download because I generally require a password on my machines when waking from sleep. Instead, I either disable the screensaver and auto-sleep settings, or use an app like Jiggler to prevent sleep/screensaver lock.