From the same article : “Sleep loss can injure the brain, and if it happens in mice, and it has been shown to happen in other species, then it probably does happen in humans,” Dr. Veasey said. “It always begs the question: How much sleep loss would cause injuries? But looking at all of this literature together, of around one week of chronic sleep loss, it really does suggest that you injured the brain to some extent.”
There is enough consensus in the scientific community about "some" connection between sleep deprivation, free radicals, oxidation stress and cell damage. Because of ethical issues since we are not allowed to directly force stress a Human (the article states: there is currently no ethical way to measure the degree and kind of cell damage caused by sleep deprivation in the locus coeruleus and hippocampus of a living human.) we do it on genetically well-matched species like Fruitfly, Mice etc. We then use statistical inference to extrapolate to Humans and see how well it matches with self-reported/observed data.
Importance of Fruitflies in Human Biology research : https://science.nasa.gov/science-news/science-at-nasa/2004/0...
Sleep, Death and the Gut (very good article) : https://hms.harvard.edu/news/sleep-death-gut