I set the alarm on my cell phone and sleep w/it under my pillow. I set it for about 20 minutes before I and/or everyone gets up in the morning.
I've been sleeping with the phone under my pillow for years now and it just blended in well with the whole charting thing. The alarm only wakes me up and not the whole house. Plus, it's usually dark when I get up for the day, so I can check the temp by the light of my phone

Good luck!