You should at least monitor your deep sleep using a smartwatch. Less than 1.5 hours and I would be worried.
I am not too worried about Alzheimer's as it tends to start pretty late in life (I think average onset is around mid-60s?). If I get that and we don't have a reliable cure by then, I wouldn't really mind ending it quickly after getting the diagnosis. I'm a bit more worried about heart disease as that tends to hit earlier.