I was annoyed that the Windows "automatic maintenance" was scheduled to run every day at 1:00AM, and it was configured to wake up my machine in order to do so. While I was able to change the time, I could not uncheck the setting to wake up my machine as it was grayed out: Screenshot #1
Here's how to disable Automatic Maintenance in Windows 8 and keep it from waking up the computer:
Disable "automatic maintenance" in Windows 8 - Super User
"You can do it by task scheduler. For this open the task scheduler by typing task on the Modern UI under the Apps and you will find the Task Scheduler at the left side click it and open. Now go to following path
Task Scheduler > Microsoft > Windows > Task Scheduler"
Screenshot #2
Apparently, disabling the task is temporary. We need to disable the triggers as per this comment:
"While you can disable the "Idle Maintenance" and "Maintenance Configurator" tasks, under \Microsoft\Windows\TaskScheduler, they will get re-enabled by the "Maintenance Configurator" task, which by default runs at 01:00 every day. In addition, it has two custom triggers, which cannot be viewed or edited using the Task Scheduler console.
Even as an admin, you don't have permission to disable the "Maintenance Configurator" task, though I haven't tried any "tricks" to do so - If Microsoft has gone through these lengths to prevent you from disabling it, it's probably a bad idea to do.
The relatively "clean" way I found to disable Idle and Regular Maintenance, that seems to still work after the "Maintenance Configurator" task has run, is to disable the triggers of the "Idle Maintenance" and "Maintenance Configurator" tasks.
The task will remain enabled, but with triggers disabled, it won't actually start."
So here is how to do that:
Screenshot #3
Screenshot #4
While you're at it, you may want to change the SkyDrive Update from kicking off every day at 4:00AM as well:
Before - Screenshot #5
After - Screenshot #6
Hopefully this (and putting the tablet in airplane mode) will help the device preserve more battery life while in sleep mode overnight.