About eight times in my life I've been close enough to death to have the whole world "slow down" and other really weird stuff go on. What I tend to call an "overdrive" state. It's saved my bacon at least some of those times.
You *cannot* simulate it. Trust me. Ain't no way.
In my personal experience, it is NOT just a normal adrenaline dump!!!
Fine motor skills are *retained*, contrary to a lot of what you'll read. (I know this for a fact because six of those cases happened while piloting motorcycles, in which I was able to use throttle, brake and clutch with my hands perfectly.) Emotions go flat. But I could still make moral judgements, based on the one such case that was (more or less) "combat related". (Quotes because they backed down.)
It's not AT ALL the same as "berzerker rage". I hit *that* once at age 12, swore never ever again. Absolutely horrible, that...and a real good way to get killed. The whole "watch your six" concept goes flying out the window on fire with burning crap taped to it's butt. Ghaaa. No. Bad idea. Don't ever go into a fight full of rage. Ever.
Anyways.
In the correct "overdrive" state, it's triggered by a threat to human life - seven times it was mine, once it was somebody else's out of those eight. Either is OK. Takes under a second to get into it, the "peak" will last between five and thirty seconds tops, then you "crash" afterwards for at least five minutes. When you look at the speed, severity and "peakiness" of this rise/peak/crash cycle and compare it to any other known drug, you become very VERY afraid of screwing around with this for kicks or even practice. Makes crack cocaine look mild as hell, whatever it is that's doing all this (likely some sort of cocktail). It is nothing whatsoever to play with!!!
You CAN recycle rote muscle memory while in that state...in other words, something you've done a bajillion times and can do well, you'll be able to do better. Your muscle memory drills aren't thrown out. If they were I wouldn't have been able to pitch a 450lb motorcycle near-sideways at 40mph in the rain and pull back out of it 4ft to the right to dodge a car. Or do any number of other really intense stuff on two wheels
. So yeah, by all means keep your shooting practice up, your draw-and-fire drills (unloaded if you don't have access to your own range or some nearby empty wilderness), etc.
But...the "add stress for realism" movement...yeah, I don't think so. There ain't NO SAFE WAY you could simulate the stress I've seen.
No way in hell.