This wake up from sleep thing might also depend on the firmware version running.
Different firmware versions, often different kernel versions, etc. ...
This thread originated at a time when firmware (and kernel used) was considerably different (I did just scan the first page or so of the thread and I don't see where anyone documented the firmware version being run).
It might be helpful to the debugging to hook into the going to screensaver and wake from screensaver events.
Note: If the USB cable is plugged in, then 'going to screensaver' does not imply 'going to sleep'.
We have a worked example of that here:
https://www.mobileread.com/forums/sh...d.php?t=198484