I’ve encountered various devices connected with HDMI cables turn ON in the middle of the night. HDMI cables provide a mechanism for Cable Boxes, TV’s, Receivers, DVD Players, etc. to communicate with each other. This capability has various names, CEC (Consumer Electronics Control) is the official name, but some manufacturers give this capability a proprietary name. The goal is to provide one touch operation. If the user drops a disc into a player and presses Play, the system will figure this out, turn ON the proper boxes and select the correct input. This is convenient until one of the boxes, particularly a Cable Box, updates its firmware in the middle of the night, then turns ON. The other elements in the chain then turn ON too and a TV program comes blasting through.
Make sure that no alarms are set.
Are you sure that BEAM is emitting the sounds. Could this be some sort of notification from the TV?