What do you think about this?
Basically take a bunch of sleeping pills and when you are close to falling asleep pull a plastic bag over your head.
This was the predecessor method to the inert gas method.
The protocol, as I've read of it, is to build your exit bag just the same as you would for inert gas: a turkey-size oven bag with an elastic drawcord around the neck.
When you're ready, take a heavy dose of sedatives.
Put the bag onto your head, but hold the elastic open with your hands, so that you can breathe freely without the CO2 buildup causing your hypercapnic alarm to trip.
Do not squeeze the air out of the bag. Contrary to the inert gas method, you want a good reserve of breatheable air in the bag.
As you hold the bag open, position your hands so that when the sedatives take effect, your hands will fall away and allow the elastic drawcord to close the bag around your neck.
Now wait for the sedatives to take effect.
The theory is that when the sedatives kick in, your hands drop away and the bag closes. The residual air in the bag allows the sedatives enough time to fully incapacitate you before the CO2 buildup trips your hypercapnic alarm. By the time the air runs out, the sedatives have rendered you incapable of removing the bag, and you suffocate.
My understanding is that it is very important to position yourself so that the bag cannot be displaced by any jerking or twitching, as your (sedated) body still attempts to react to the hypercapnic alarm.