the weirdest thing is happening and I can reproduce it quite reliably.
I put my Mac to sleep by closing the lid and check it has gone to sleep in the evening. In the morning, both my iPhone and iPad go out of Sleep Mode at 8am so all previous Reminders & notifications fire up then. I happened to be next to my desk with my iPhone in hand and I noticed the Mac waking up. It is very quiet so I went near and heard the fans being active...
I used the Consolation3 app from H. Oakley to browse the log entries and the Mac is indeed asleep before 8:00am but suddenly wakes up some seconds later. A lot of entries about remindersd, fetching CoreData, CalDav ...
I have not yet upgraded to the new Reminders because of shared lists with family members but if that is the (proven) reason (not just something Apple would say to do to try things out because there is no way back) I will upgrade.
Do not disturb is active until 7am, but the Mac awakes at 8am. PowerNap is not enabled.
Does anyone know what is happening here? Is there any other check I could/should perform?