I have an iPhone 8 and an iPad mini 4 (both with iOS 12) that seem to have the same problem.
For some reason, they randomly turn on the home screen when they are resting, as if they just received an insert notification (although they do not have it).
When the start screen is turned on randomly, it will not turn off without manually pressing the lock button. So if this happens in the middle of the night, the battery simply runs out.
Any idea why this could be?
Please see the screenshot below of the configuration application to block on the iPhone.