My friend has worn an alarm. either as a pendant or round her wrist for years now. She started when her husband became bedridden and carried on with it after he died because she now lives alone. Recently she went to bed with the wrist alarm on, rolled over on it while she was asleep, and set it off. She vaguely heard her phone ringing but thought it was a scam call, because who would ring in the middle of the night? She was very surprised to be woken up by strange men in her room, wanting to know if she was all right! Still, it's nice to know that they do come out if they think something's wrong.