My printer (a high-end color laser) behaves itself very well, but if I leave my Thrive tablet powered on in the charging stand with the screen off, it will occasionally turn the screen on (maybe when it receives an update or an email?).  Although it turns the screen back off right away, having that sudden blast of light in the middle of the night can be just as disturbing as your printer!  I have to remember to cover it when I leave it that way.