I stress the term "oxygen deprivation" here because I do not do any of this with any sort of neck play, strangling, choking, or anything that restricts blood flow to the brain. I personally don't feel like that's safe, and furthermore it's totally different reaching blackout from oxygen deprivation than from blood circulation restriction.

That said, I am a former lifeguard and CPR class instructor. Additionally, I have many years of experience with breathplay, smothering, and holding my breath. But I can actually voluntarily hold my breath until I pass out. Granted only maybe 1 in 4 attempts is successful, but I can do it. I have also reached blackout too many times to count by partnered breathplay (generally while subbing).

I only engage in hard smother sessions with experienced partners who I have built up to that level with and who are knowledgeable. But to me, altho it can be torture, it's sweet sweet torture. I don't know why, but in addition to enjoying having my breath restricted, I also have additionally the more specific kink of extreme oxygen deprivation suffering and torture.

I think blacking out has gotten a bad name. When you know what you're doing, have your relative youth and are healthy, preferably something like athletic, as well as no medical conditions, it's pretty safe. Granted those are a lot of ifs. Does anyone else have experience blacking out? Do you engage in the practice? I rarely stay blacked out for more than 1-1.5 minutes but there's been a good few times it was longer. Often it's less. Can't stress how important safety is!

Not looking to sext so DMs might not be the best place to reach me... but I think having a discussion here in the comments might be interesting.