I reckon they’re clever enough to bypass an alarm system, especially if they’ve installed it themselves. Besides, there are so many people who no longer bat an eyelid when an alarm goes off; the same goes for car alarms. I hear them regularly, but no one ever goes to check – not even the owner.
Given that electricity is becoming expensive because it’s getting scarcer, everything will soon be cut off and we’ll all be shopping for free.

@maxart has given a good reason why we wake up at that time... imagine you suffer from anxiety and immediately grab your revolver and shoot someone because you hear something...