why does my computer awake from hibernation without action / spontaneously?

Answer 1

go to scheduled task in control panel
click add scheduled task
select a program
set the time
And in it Open Advanced when i close
In it
check in the check box implies 'Wake My computer to run the pgm'
Then Hibernate

Answer 2

It could be waking in response to modem and/or network card traffic. Disconnect your phone line and/or network cable and see if your computer stays in hibernation for you.