McChrystal's or anyone elses eating and sleeping habits are not among those few things. People are different, all have different food and sleep needs and all this foolishness about sleep deprivation is true but not an issue and is very much individual condition, experience, practice and metabolism related.

Carl is right that exhaustion kills and Intel Trooper is correct in noting that about 40 straight hours gets you to the point of non compos -- everyone's heard about Ranger students talking to trees...

Fuchs may be correct in stating that McChrystal is setting a bad example -- but I'm quite sure there are hundreds of 'leaders' over there setting far worse examples on many counts. A guy who sleeps little, doesn't overeat is probably one of the most benign bad examples I've run across. Not to mention that everyone in combat gets too little sleep and eats poorly --sort of goes with the territory.

That said, combat forces you to do without sleep at all levels from PVT to GEN; the body and mind adapt as best they can. Some do it well, some less so. It's a non-issue. Everyone adapts as well as possible and most get to the point where they can go 24-30 hours or so at a stretch without too much stress and can do that several times over the period of a week or so before they need an overnight sleep. It usually works out as things cycle.

Thus, to Schmedlap's question
Do any of you look back upon your deployments and think, "boy, I thought I was thinking straight, but in hindsight, I was way too tired."
my answer is Sure, several times in all of them. Not much could have been done about them, though. Until we do combat as shift work (not unthinkable...) we're going to have that problem but as Slap says:
"...all a GI needs is a cigarette and cup of Coffey now and then and everything will be fine."
That's still true. Unfortunate, not ideal, not even marginally good -- but then war is unfortunate and not an ideal situation and there's nothing good about it...

As for McChrystal and the automaton bit; Generals are people. People vary. Everyone doesn't make useless chit chat or idle comments answering inane questions at length without saying anything of substance (thank goodness!). Creighton Abrams was one of our better products, probably with Ridgeway the best post WW II type and he was not a chatterer -- his best line was "Generals should be noted for their silences."

Note lengthy answer with little substance.