The white rock, visible enough above the brush, was still some eighth of a mile further down the spit, and it took me a goodish while to get up with it, crawling, often on all fours, among the scrub.

They are alert at bedtime and sleepy when it is time to get up, and this may have nothing to do with how fatigued their bodies are, or how much sleep they must take to lose their fatigue.

This isn't easy territory. Get it wrong and you end up with some truly bizarre results.