I think it would be time for a little education about how important it is to leave the machine alone, and if that didn't work then maybe a little punishment might be on order.
Why not lock the bedroom door?
Many CPAP machines, including your PRS1, have an auto start feature that will turn the machine on if you're masked up and breathing. Unfortunately, the autostart function may not work if you use a full face mask.
Turn on autostart, mask up, then turn off the machine and see if it comes back on for you.
Get the free SleepyHead software here
for information on the main alternative to CPAP.
If it's midnight and a DME tells you it's dark outside, go and check it yourself.
Wondering if parents with children on CPAP have a problem with the kids turning the machine off?
My PRS1 will start automatically with my FF mask... The problem could be solved with a locking cabinet - put holes in it for hose and electrical cords... use on a lower shelf, have a place for supplies, and you'll still have room for clock, tissues, on top.