Schedule Sleep and Wake in Mac OS X
You can schedule your Mac to sleep, wake, shutdown, or boot up at any regular interval using the OS X System Preference ‘Energy Saver’ schedule settings, here’s how:
* Launch System Preferences
* Click “Energy Saver” (it’s the coiled eco-friendly lightbulb icon)
* Click the “Schedule” button in the lower right portion of the preference pane
* Set whether you want your Mac to sleep, wake, boot, shutdown, or whatever
* Set the appropriate times
* Click ‘OK’
Now your Mac will be scheduled to boot, shutdown, whatever! This is really handy to setup so that your Mac will be up and waiting for you before you arrive to your workstation, or so that it will sleep through the night and conserve power. Try it out yourself!

[...] Real Time Clock Alarm, is generally from wake-on-demand services like when you schedule sleep and wake on a Mac via the Energy Saver control panel. It can also be from launchd setting, user applications, [...]
Any idea how to disable the scheduled sleep warning that appears about 2 minutes before the computer is scheduled to go to sleep? I’m creating a kiosk and the client would like to put the box to sleep or shut down at night and wake it up the next morning. But, we don’t want to give any users the option to disable this.
As it is, a notice pops us about 2 minutes before scheduled sleep or shutdown. Any idea how to disable this?
[...] Quickly resume exactly where you left off; sleep and wake can be scheduled or even done [...]