Yes. It's one of the more painful ways to kill yourself. First you pass out but you're still alive for a few minutes until lack of oxygen finally takes you. If you're found in time and revived you may have brain damage.
The only way
hanging is a quick death is with the right drop. There's actually a formula to calculate how long of a rope you need, based on bodyweight, to snap your neck instantly. It's not a short rope either. I think it's something like 11-12 feet if you're around 160lbs.
It seems like they're trying to punish themselves before dying because that's exactly what they're doing. It's sad when people commit suicide as its a waste of life and really hurts those around you.