RE: sleep debt
What is known is that almost any physiological and psychological damage caused by deprived sleep is restored by one good night's sleep. However, sever damages to the circulatory system and endocrine system will take longer and restoration is not based on getting additional rest.
As for what is going on with people starting CPAP is that there is a settling in period, where they are relearning sleep patterns and expectations, and this may be mistaken for "making up on sleep debt", IMHO. But this has nothing to do with settling a perceived debt due to privation at all.
As for CPAP usage preventing strokes and heart attacks, that is correct, but not because the new sleep pattern "cures" the damage done, but rather prevents the damage form getting worse, and in the long run will help restoration of the most sever damage.
RE: sleep debt
If you have had a "bad habit" for fifteen years, how long to you think it will take for you to get into a "good habit", especially if you are relying on a machine to help you into it rather than conscious effort? The body has trained itself to do things one way and must now learn to do things another way - that can take time and that is what is going on here.
RE: sleep debt
I think they deal with debt differently in Switzerland. As for the US, several well respected physicians that I am acquainted with believe that sleep debt is real.
RE: sleep debt
Doesn't matter how much I should sleep. Even with a near perfect CPAP night I not going to sleep more than 8 hours and more likely not more than seven. I simply can't sleep any longer than that. Since starting CPAP I feel much better but still take a 15 to 45-minute nap about five days a week. I take it because I can (retired). On days when I don't nap I still only sleep 7-8 hours.
"Sometimes the magic works . . . and sometimes it doesn't" -- Chief Dan George in the movie Little Big Man