XPS 13 comes out of hibernate by itself

Hello!

The following has been happening every night. Studio XPS 1340 -> P9600 - Win7 x64

When I go to sleep at night, I put my XPS 13 into hibernate from win7. When I wake up in the morning, it is on.

Sometimes when I go to sleep at night, I also unplug the power because the blue light from the power adapter is annoying. When I wake up in the morning and try to turn on the system before plugging the power in, it does not work because the battery is drained meaning at some point it turned on itself on at night and drained the battery. When I plug the power back in and boot, win7 shows the battery completely empty.

Does anyone have any ideas why my XPS 13 comes out of hibernate overnight? Is there some setting I am missing? This happens with and without the network cable plugged in so I am pretty sure it is not a WOL thing. It has also happened both with and without an external monitor and other peripherals plugged in.

Thank you!

M.