A very useful program for me has been
Sleepy.
It can be defeated (in V.5) by altering the bios, but V6 is going to synch up with the internet.
When you install Sleepy, you choose which days and at what time it should shut down your computer. From then on...
When you turn on your computer, Sleepy starts automatically and shows when it will shut down your computer.
Sleepy runs invisibly in the background while you use your computer.
You can open Sleepy Settings to see or change settings, and you can still shut down or restart your computer normally.
Several minutes before shut down time, Sleepy will show a warning message (you can choose whether to show messages, and when to show them).
At shut down time, Sleepy will show a "Shutting down..." message, and then it will try to shut down your computer (if you have unsaved documents open, you'll be prompted to save them).
If Sleepy's first shut down attempt didn't work, then a few minutes later, Sleepy will
force your computer to shut down (and if you still have any unsaved documents open, you
won't be prompted to save them).
Check it out. I have a bad gaming habit and this is about all I can use to keep me off the 'puter late-night on work-nights. I even had my gf password protect it so I can't change the settings ;-)