Carlos is right about SMS. I run a food plant and we built nearly the same „only at night, only if it lasts“ alert for cold room doors, so here’s what worked for us.
Alarm rules don’t have a time window, so do the logic in a Rules card instead. Put the three bed sensors under an asset for the wing (Sites & Assets), add a Rules card on a dashboard locked to that asset, and write:
When: A value changes, device = every device of the bed sensor profile, value bed_occupied, becomes 0, and stays so for 10 minutes. Only if: A time window, after 22:00, before 06:00 (a window can cross midnight). Then: Raise an alarm, type bed_exit, severity Major, on the device. Then Tell people.
With „every device of the profile“, each bed has its own trigger and its own 10-minute wait. The trigger fires once when the value turns 0, not on every message.
Two details. Make the sensors send bed_occupied as 1/0 every 30 seconds, not only on change. And the alarm you raise stays open until someone clears it (a Clear action, a flow or a person), so the carer clears it after checking the room, which also gives you a record.
For reaching the carer: Tell people goes to roles, and roles get the bell plus any linked chat app, not e-mail or SMS. If she uses a chat app on her phone, link it in her profile and that’s the quickest route. For a real SMS, add a flow with a Notify block and her number. The triggers page has the „stays so for“ details.