Your body within reason can get somewhat used to little or no sleep. Ft. Polk Louisiana A.I.T..1968.
Some night training setting up a perimeter were gonna get attacked shoot blanks have fun playing Army etc. etc. Morning ah time to hit the sack cool.
Sarge comes over to me. "Get on the truck yah got K.P." What? I been up all damn night you frigging idiot I am tired mom would let me sleep you frigging jerkoff don't you frigging stupid....."
Of course I did not say that to his big ass.
Yes Sargent.
But I got my second wind and learned you can go without sleep. To long? nah as the article says the body and mind fall apart.