Actually, they can and do climb walls and ceiling and then fall onto the bed.

Get diatomaceous earth, pesticide specialty store or garden center (not as good). Powder the carpets espcially near walls and bed legs and door to room. Also, take off outlet, switch covers and blow some in there. Put mattress in special bed bug proof bag and seal zipper with duct tape. If you live in hot climate. Put those sealed black garbage bags in the hot sun for th entire day (free high heat). If not, commercial hot dryer. All your clothes. If you find a pesticide specialty store, they can sell you the stuff and sprayer. Follow their instructions. Do it again in 10 days. Had 'em once. Not fun or easy. All above has to be done at same time