Because of the strenuous mission requirements, the Air Force has provided for our safety thru AFIs, regulations, and flight restrictions to include "go-pills." These amphetamines, issued through flight medicine, help crewmembers remain alert when there is no opportunity for sleep.
I was the only member of the flight who did not sign out "go-pills" and approximately three quarters of the way through the vulnerability period was so sleep deprived that I turned to the aircraft commander and asked him to fly for the next 30 minutes.
The other lesson I learned is that "go-pills" take about an hour to kick in.
So to be prepared, my recommendation is check out the "go-pills" from the flight surgeon.