I suspect you would only be able to do this in theory…
If you were able to hold on until you passed out, wouldn’t the respiration begin as an automatic reaction? It seems you are directly imposing this unnatural will on your respiration process… once that imposition has ceased (i.e. you pass out) the natural action should continue??
Does anyone know scientifically if it is possible?
Without using any aids, like a rope or a plastic bag or something, no. You’ll simply pass out (if you can even hold your breath that long) and begin breathing again naturally.
You’re right – you can’t hold your breath like that.
And from a conversation with a relative who’s a doctor, it probably won’t even last long enough for them to pass out. He said very few people are able to use their concious willpower part of their brain to override the brain’s autonomic (sp?) reflexes.
I know it’s not scientific proof, but evidence is readily available. Just ask any mother who’s raised a 2-year-old, and ignored them saying “I’m going to hold my breath until I turn blue”.
Only underwater.
Being Held underwater. I heard that you can’t drown yourself.
However, many people can hold their breath until they get close to passing out. I knew a gal a few years ago who managed to get herself addicted to the experience. She did it unconsciously when stressed, or sometimes it seemed just for the hell of it. Her doctor did not approve, and issued all sorts of dire warnings about cumulative brain damage. Googling on autoasphyxiation turns up some pretty wild stuff about the dangers of nooses and such, but nothing definitive on simple breath holding.
Well, if you pass out you could fall down and hit your head… My little brother once yelled until he passed out 
That was fun.
I haven’t heard that before. Surely a determined nut could keep swimming down until he could no longer hold his breath. Sure, he’d float to the surface even with his lungs filled with water but depending on the time it took to reach the surface resuscitation might not be quick enough (if there was somebody around to do it).
If you tied a sack full of rocks to your leg and then tossed it into a lake you’d soon drown yourself…don’t try it.
But if you can drown by accident, why can’t you drown yourself? I mean, jsut jump into deep water.
Yes but instinct would take over and you would swim to safety, even if you were a non swimmer all you need do is lie on your back arms and legs spread head back and hey presto, you float.
Those that die by accident have usually hit their head on something or are semi concious for one reason or another
By my understanding, a non-swimmer wouldn’t know how to float on the back… or even that lying on the back keeps one afloat.
I would imagine that the non-swimmer would flail about in the water until he passed out from exhaustion… and then drown.
Of course you can drown yourself - thousands of people every year drown through being unable to swim. They panic, thrash around, and either through this or exhaustion, they eventually take in lungfuls of water and die.
GOUDA/JJIMM: These are classed as accidental drownings but really this isn’t answering the OP
Are you suggesting that instinct would cause a person to relax anf float on their back? I really doubt it.
Of course you can drown yourself on purpose; you could certainly deliberately inhale water and although this might not kill you straight away, an intense fit of coughing and gasping, while you are treading water, would probably result in the inhlatation of more water not to mention diminishment of muscular control to keep your face out of the water.
I had heard somewhere (anecdotally) that in times gone by, many sailors couldn’t actually swim and if forced to abandon ship, they wouldn’t even try to stay afloat, although this does seem rather strange.
Sorry for continuing the hijack, but I’ve heard that the fishermen on Lough Neah in Northern Ireland deliberately didn’t learn to swim so that they would drown quickly if they fell in (this stems from a fatalistic belief that when the water chooses you, then it’s time for you to go).
Concerning the OP, my mother says that when I was a child and I didn’t get my way, I would hold my breath until I would pass out and then I would start breathing again. She asked a doctor about it and he said, “Let him hold his breath. He will pass out and start breathing again.” Mom would never be intimidated by me. She would always let me pass out and I would start breathing again. Sometimes in public places people would accuse her of child abuse. She would reply that I am doing it to myself and when I pass out, I would start breathing again. I will be 41 soon and I have never been able to hold my breath until I die.
Not everybody. The only place I ever managed that was in the Mediteranean Sea - any place with fresh water (or less salty water,) I sink like a rock.
Well obviously I generalised and will concede the point that not everyone can float…however!!
Next time you are in a fresh water pool take a real big couple of deep breaths, in,out,in,out,IN…fall on your back, spread 'em, head back and you’ll float, honestly. If you don’t I’ll send a real nice bunch of flowers and apologise to all concerned before my head is kicked in. 
When my sister was younger, she did this thing she thought was “cool” – she would lean over, take some very deep and rapid breaths, then stand up, wrap her arms around herself and squeeze while holding her breath… She’d pass out on the ground.
We grew up in Ohio.