Yep, I hear you. I just can't seem to see exactly the timing of the disconnect. It has happened almost always after overnight, but at least one morning it worked OK. It MOSTLY works during the day -- the mouse, keypad or trackpad all wake the iMAC up as expected -- but it has failed a couple of times even during the day. My disk, monitor, etc go to sleep within an hour at most. What kind of sleep would occur overnight that doesn't happen within a shorter time? Very frustrating having to reboot daily, at least.
And...btw...my MAC Air, updated the same data continues to have ZERO issues!