> UC Berkeley sleep scientists have begun to reveal what it is about fragmented nightly sleep that leads to the fatty arterial plaque buildup known as atherosclerosis that can result in fatal heart disease.
This is a causal claim, emphasis mine, which contradicts:
> “To the best of our knowledge, these data are the first to associate sleep fragmentation, inflammation and atherosclerosis in humans,” said study lead author Raphael Vallat
which is a correlative claim, emphasis also mine, and they use "linked" throughout the article, which is also correlative.
So does fitful sleep "lead to" chronic inflammation and arterial plaque, or are chronic inflammation and arterial plaque simply typical of people in poorer health and/or overweight, which can itself potentially cause sleep disorders, ie. a correlation? I'm not sure we know the actual root causes here.