Q. In regards to using an apnea respirator, When you first turn on the machine, it is at a low air pressure. This is to allow you to fall asleep. After about 10 minutes, the machine ‘ramps’ up to the preset maximum. If I use a timer, I will lose the ramping up period, and since my pressure is high, I will not be able to fall asleep

A. Please see answer 389 in this forum where Horav Shlomo Miller Shlit”a permitted the use in Shabbos of a sleep apnea machine that does not have a sensor which turns it on and off, responding to the breathing and also adjusts accordingly the pressure needed in real time, (APAP or Auto Positive Airway Pressure system) but rather the simpler continuous air stream machine. This is permitted when there is a compelling need for its use, as when the user cannot fall asleep without it (even if his life is not presently in danger), and if it is connected to a timer that automatically turns it on.

He therefore recommends that one should obtain for Shabbos use the simpler machine, which is also government subsidized.

A trial should be done before Shabbos to see if the timer set up works properly

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a