Hi
The alarm is designed to go off if you have a lost signal so whilst it might wake you up at least you will know.
If the sensor is over heating there will be a separate error message telling you its the heat.
This has only ever happened to me once in 5 years and that was in the canaries.
I sometimes have a run of lost signals but have never been too concerned as the alarm goes off to tell me and yes it can be a nuisance but thats all it is.
I'm old school and survived for 40 years without the libre which is why i simply adore it and the improvement of my control is down to the libre.
I wish you well
Tony