My two bits...humbly submitted
One thing I have not heard yet is the definition of "combat effectiveness."
This claim of maintaining "full combat efficiency" is idiocy. There is no way that efficiency after 7 days isn't lower than after 1.
The way I see it is that we should look for ways of increasing human performance in periods of extreme sleep deprivation by chemical or other means. Also, we need to come up with a better concept than simply "combat efficiency."
My personal experience with sleep deprivation.
No Sleep: 72 hours...after that you start to go down hill very quickly. I've been out to 5 days without sleep a number of times, but my personal record is 7 days 6 hrs. Most people will be completely useless on day 5.
1-3 hrs/day: You can actually survive for quite a long time this way. you can maintain near full efficiency for 3 days. After this point there is a steady decline until 5-9. After that point you tend to level out. You won't start to hit bottom for a while. That comes somewhere from 3-14 days later. At that point you will have a hard time telling the difference between when you are sleeping and when you are awake. Somewhere between 21 and 30 days you will lose that ability. At this point you still are functional to some degree, but you will start to lose your sanity soon.
(I should note that my experiences with sleep deprivation were during periods of extreme pain. I'm sure that in some way impacted my ability to stay awake. Still, in times of non extreme pain I've found this to still hold true, but I have never had to go past 10 days since then.)
Adam L