Experiment to detect sleep-disordered users via social media posts
Boston Children's Hospital and Merck did a data mining experiment on Twitter users who mentioned sleep trouble. Unsurprisingly they found those people tended to tweet more late at night, but they also found that their tweets were more likely to write tweets with negative sentiments.
Invasive or a good idea?
Yeah, I think it's a great idea. It's not a privacy invasion as they posted it on the Internet so they should not be worried about who sees it.