Get something like timeriffic to create a sleep profile that turns everything off except the alarm.
This is exactly who I have my Droid set up. I installed the app Timeriffic a few months back. I love it!
Every night at 11pm, all volumes on my Droid turn off except for the alarm volume setting which gets turned all the way up. Also, my WiFi gets turned off too.
It's a great app... I don't have to do a single thing.... it makes the adjustments for me.