It's certainly true about the link between stress and lack of sleep - both physical and mental. When my husband got sleep apnea it got so bad his blood oxygen was down to around 25% for a little while and he was in danger of getting brain damage, kept forgetting basic stuff as well as the breathing aspect and need supervision when he was driving 'cos he tended to nod off there too.
The latter caused me such stress during the day whenever we went out in the car, even for short journeys, that my sleep was severely affected even after he was diagnosed, as the noise of his CPAPP machine was as intrusive as his snoring (and his not
snoring which simply meant he'd stopped breathing) which, coupled with work-related stress relegated him to house mate status and drove me mad for nearly 20 years and contributed to the breakdown and underlying depression that cost me my job. Also caused me to forget basic stuff and going around on auto pilot so much that I twice nearly walked under a bus at a busy crossing outside Charing Cross station and got into a real mess with decision-making tasks and relationships at work...
So it's not always Alzheimers, no matter how old you are - and if people reckon they don't
snore a trip to sleep clinic is the best way to find out for certain! It saved Pete's life basically, because he'd have died 8 years ago without the diagnosis. Too late to save my sanity, but at least I get a decent night's sleep these days (moving out of the bedroom was the best thing ever for me and the marriage to be utterly brutal