Help me find the offending process waking my Windows 7 PC from hibernate every night

I had the exact problem like the OP, Win7 32Bit, PC hibernation and it woke up at 3:57am precisely every night, but there was nothing noted in the log and the powercfg -lastwake gave no information.

The problem was the Windows Media Center. Once, I even caught it red-handed downloading some updates right after the PC woke up, so I disabled the auto-update in the settings. So when the problem persisted I wasn't thonking of the WMC as the culprid anymore.

But it turned out that even though I turned it off within the WMC, the task within the Task Scheduler was still up and running. To disable the task simply open the Task Scheduler, navigate to Task Scheduler Library\Microsoft\Windows\MediaCenter. There should be the mcupdate_scheduled task. Disable it – problem solved!

I was having exactly the same issue of my laptop waking up after 6 hours of sleeping. I have found that the cause of the issue in my case was the advanced power settings for hibernation, which was set to hibernate after 360 mins (6x60min) of inactivity.

How to check and disable:

• Go to Control Panel → Power Options → Change plan settings → Change advance power settings.

• You will get "Power Options", where you have to navigate to "Sleep → Hibernate after" and disable hibernation for both "On battery" and "Plugged in" modes by changing the default value from 360 to 0.