You want it darker? Growled the late Leonard Cohen on the title track of his final record. To which the only conceivable answer is surely: “Er, no, you’re right, Len, thanks for asking”. In an uncertain winter, more shadow is surely the last thing we need. Bring on the light, eh?

Well, yes. Only, not too literally. Our world is lit up as never before, and not in a fantastic way. Where once the bustle of the afternoon gave way to the softness of starlight and the spell of the moon, today everything’s illuminated. We banish the dark at every turn. And as it fades to gray, so do we.

Romantic whimsy? Far, from it. Lighting up our world, 24 hours a day, plays havoc with the natural rhythms on which so much of life depends. For millions of years, it’s evolved in sync with, and dependent upon, a daily shift from light to dark, light to dark, regular as clockwork, ages before we ever dreamed of a clock. Not any more. Scientists say that cloudy skies over cities at night are now around 1,000 times brighter than two centuries ago – and the skies glow spills out way beyond town limits. Messing with that ancient circadian rhythm is disrupting everything from migratory patterns of birds into the hatching of sea turtles, and retains at least part of the blame for the decline in insect numbers and other species, also.

Species like us. We might be daytime animals, but weredesigned for the darkness, too. There’s mounting evidence that circadian disturbance is leading to everything from attention deficits and depression, to suppressed immune systems and growing risks of cancer and cardiovascular disease.