It's a strange and necessary thing, this nightly bout of unconsciousness.
Without it — or indeed enough of it — we can't ever hope to function normally. Mornings are spent walking around in a remorseless fog, afternoons find a man struggling to stay awake — stand at attention, soldier! — and the evening is when the body finally chugs into second gear, ready to take on all-comers.
But finally, when things just get rolling, it's time to halt the proceedings and lay down again. The clock says yes, the burning eyelids say yes, but your brain says no! We just got started!
And so the fight begins, destined to repeat itself until some Good Sense strikes us at the right time, and we shuffle off, "perchance to dream," as a fellow from Denmark once opined. Tough to do, when an entire day's worth of work is begun after the Sun goes off to sleep, itself.
"Circadian" — circa, plus diem. Fickle mistress, that rhythm.