I just got my new 27" 5K iMac and it's awesome. But one issue that I'm seeing is that the Mac is not staying asleep. I usually manually put it to sleep and it does go to sleep. But the next morning, I see that it was woken itself up during the night. I know that also because I get a ton of "disk not ejected properly" messages (because I have external drives connected) when I try to access it the next morning. In the energy saver preference setting, I have none of the check boxes checked ie. wake on network access, power nap etc..