Out of a sound sleep at 3:00 this morning, one of my smoke alarms went off. It was either the one just inside my bedroom door or the one right outside that same door. They are hardwired in with a battery backup. I have five in all and they were all replaced this spring. I ran around the whole house like a chicken with it’s head cut off looking for something and found nothing. Being a former firefighter you can only imagine what I was going through. After about 45 seconds it silenced and everything is fine now. Any ideas!