When I'm done working with my computer, I usually put it in a sleep mode. But recently (probably after some windows update), in the morning my computer was always on.

Reason

First I checked Event Viewer and found following record:

The system has returned from a low power state.

Sleep Time: ‎2015‎-‎07‎-‎29T20:54:24.378170500Z
Wake Time: ‎2015‎-‎07‎-‎30T02:18:17.109989000Z

Wake Source: Timer - Windows will execute 'NT TASK\Microsoft\Windows\TaskScheduler\Regular Maintenance' scheduled task that requested waking the computer.

Ok, now I know that "Regular Maintenance" waking up my computer at 2AM.

The other way to see who is doing this is to check  waketimers.

  • Run cmd.exe as an Administrator
  • Execute command  powercfg /waketimers

You will see all task that can wake your computer up

Fix

  • Open Control Panel
  • Go to Action Center (System and Security group)
  • In Maintenance group click on Change maintenance settings link
  • Uncheck "Allow scheduled maintenance to wake up my computer at the scheduled time"
  • Press Ok

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