No need to stop to rest, and no need for caffeine. There are plenty of good techniques to crush road hypnosis. For instance, turn your head and actually look at something out the right window. Face forward again. Then turn and actually look at something out the left window. Face forward again, much refreshed. Roll down the window to the point where the noise, wind, and cool are slightly annoying. Turn up the radio and keep it on scan.
Yeah, maybe if it's 10 hours or under... Anything over that and nothing but rest will help.