I'm not saying "disturbed sleep", which I believe you are defining as apnea or other respiratory issue, should not be looked at. But even if it is, that does no

I'm not saying "disturbed sleep", which I believe you are defining as apnea or other respiratory issue, should not be looked at. But even if it is, that does not answer the age related decline in SWS. Even if there is no other health issue, SWS declines with age. The decline of SWS is linked to increased amyloids, which is linked to Alzheimer's. Yes, apnea also has an impact on SWS, with the same relationship to amyloids and Alzheimer's, but solving the apnea does not solve the age related decline.