Well, that was interesting!

[Kogarashi]

I have found that the only thing that will keep me awake when I'm starting to doze, is conversation.

There is something about the thinking required when conversing with someone that will keep me alert. The radio, caffiene, sugar, etc, none of that has any notable effect for more than a minute or two.

^-.-^

Same here. It's too easy to zone out while listening to the radio, and caffeine doesn't quite work right for keeping me awake (buzzed, yes, but not awake). Holding a conversation with someone, on the other hand, works wonders.

And my family had a standing agreement that the driver was in charge of the radio, and thus could keep it on to keep themselves awake regardless of whether or not the relief driver(s) wanted to sleep.