iMac wakes from sleep because of 'Sleeptimer'

Hi all

I have a problem with my iMac. During the night it automatically wakes a few times (screen doesn't go on, but I can hear the optical drive spinning) and after a few seconds it goes back to sleep.

So after some reading on the internet, I checked my console to see why it does that and according to my Mac it's because of 'EC.Sleeptimer' but my sleeptimer isn't even on? (you can see my options in the attached images)

As you can see, my settings should be just fine to keep my Mac in sleep ALL the time. I've already tried resetting my SMC, but that didn't fix it.