When I read the thread-title, I (naturally?) thought first of horror-flicks.
And after reading the rest, I still will say - some horror-movies.
To be more precisely: movies belonging to the genre, so aptly named "torture porn".
When I was younger, I could watch everything. Some things may have somewhat damped your appetite (no eating while watching some gory scenes), but you got over all of it, without losing a night of sleep thereover.
But I notice, more and more, that -the older I grow- the more sensitive I become to "realistic depictions" of,...well...torture, and the infliction of pain and injuries to people in general.
That change of my perception in regard of such depictions may have to do with the fact, that I saw a lot of this shit IRL, and it kinda loses its "charme", when you know, that these things are happening for real.
So, when I read something about movies like "Hostel", "A Serbian Film", etc...I really feel no urge, to watch these.
I guess, when you're young(er), you think you have to prove something to yourself (and your buddies), but with growing age, that thinking dwindles.