I think this study is probably true, but it it confusing causation with correlation? Correlation is not causation; people in ill healthy might well sleep poorly.
2022-10-25. Emphasis added.
Sleeping for five hours or less a night if you’re age 50 or older could increase your risk of getting two or more chronic diseases as you age, research has found. The study was published on Oct. 18 in the journal PLOS Medicine.
...The study found that those who slept five hours or less around the age of 50 were 20 percent more likely to have been diagnosed with a chronic disease and 40 percent more likely to be diagnosed with two or more chronic diseases over 25 years, than those who slept seven hours a night.
Additionally, sleeping for five hours or less at the age of 50, 60, and 70 was linked to a 30 to 40 percent increased risk of two or more chronic diseases when compared with those who slept for up to seven hours.
WIND: sleep is critical. I’m one of those who has always needed at least 7-8 hours to function well, and 10 hours if training hard. But my post-COVID long COVID issues raised that as high as 18 hours a day for the first year of trouble.