Okay, I suppose going by the strict definition of "social media", it does. The study cites "Facebook, Instagram, Twitter, and TikTok" as examples, however.
Do you believe there is a fundamental difference between these sites, and something like HN (despite both being social media)? I feel like there is. I know this might come off as "I use the superior, intellectual site" or something like that (even though I use the other sites occasionally). But reading tech-related news and comments about it feels very different than scrolling through funny videos on TikTok.
I don't mean to say HN is any better in terms of mental health than either of the others - I spend more time on it than I really should. But I never leave it feeling depressed or jealous like I do on more common social media: I always feel like I learned something rather than watching a meme I'll forget in 30 seconds.