My smoke alarm went off

A loud beeping then ‘attention fire’ ‘attention fire’!

First I thought the fridge alarm was going off until the voice started. Then I remembered we had replaced our old smoke alarm because it had started to beep every five minutes even when we changed the battery.

So where was the fire? No sign, not a sniff or sight of smoke. No hot spots, I’d turned off the heater, the lights were mostly out. The kitchen door was shut and I’d only had the kettle on for a cup of decaff coffee.

What could have set it off? I wonder if a spider has moved in? I stayed awake till 7am waiting for it to go off again. No smoke without fire? So tired! Be alarmed, be very alarmed!