Just wanted to say thanks for the various threads found here, including this one, our 98 Grand Cherokee started doing "haunted" things as my girlfriend put it, heh. First just once in awhile she'd go over a bump and the interior lights would flash on and off and over time it had gotten more and more common to happen on lesser bumps.
Last week the alarm went off in the middle of the night so that was pretty much the last straw for me, so started investigating and sure enough, thanks to all the threads here, it pointed me to the rear glass hatch switch. I couldn't tell you the last time we actually opened that glass part of the hatch, nor could she, and she bought it new in 98.
Long story short, removed that rear plastic cover on the rear hatch to access the wiring and removed the sensor that just snaps onto the end of the latch mechanism for the glass hatch and the issue has gone away. For as little as we've ever used it, not sure its worth replacing the switch, and I dont see someone trying to break into it through that window when they can see the alarm is on anyway.
Here are a couple other threads I read through to help point me in the right direction.