Advances in lighting have banished the night (Image: Michael Vanmede Boas/Gallery Stock)
Read more: 鈥�The night: The nocturnal journey of body and mind鈥�
LOOK up at the sky tonight and count how many stars you can see. Ten? A couple of dozen? Then you鈥檙e in good company. Several hundred thousand stars should be visible on a clear, moonless night. Yet 75 per cent of the world鈥檚 population has never seen the majesty and wonder of the star-strewn Milky Way 鈥� and they never will.
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That鈥檚 because more of us than ever are living in cities that are getting bigger and brighter. All that light from buildings, street lamps and vehicles is scattered by dust and gas molecules in the lower atmosphere, producing a diffuse glare known as skyglow. On some nights, it can outshine moonlight.
And there鈥檚 little respite. From dusk until dawn, 365 days a year, artificial lighting is turning night into day. 鈥淪ociety has been sold this as progress,鈥� says Bob Parks, executive director of the . 鈥淎t some point, it has to come to grips with the scientific research showing that this may not be a good thing for humans or any other organism.鈥�
Last year, the American Medical Association confirmed that night-time lighting can exacerbate (see 鈥�Night special: Why they call it the graveyard shift鈥�).
Humans can draw the curtains or reach for the dimmer switch 鈥� not so plants and animals. Night-time light affects many species. City blackbirds start their dawn chorus up to 5 hours earlier than their country cousins because of the combination of . While some species of bat forage for insects attracted by street lights, other species avoid lights so that . Nor are plants immune: , leaving plants vulnerable to extreme cold or dry weather.
. 鈥淚t changes mating behaviour. It changes migration behaviour. It changes predation,鈥� says Parks. Predators can extend their feeding by several hours. 鈥淭hat can dramatically change the balance.鈥�
But it鈥檚 not all doom and gloom. Just as advances in lighting have banished the night, they could return it to us. The only control we have over sodium and halide street lamps, the main types of lighting in use since the 1950s, is to turn them on and off. However, advances in LEDs mean we are on the cusp of fine-tuning outdoor lighting to minimise and even reverse its negative effects. The newest lighting systems are capable of directing beams only where they are needed, rather than blasting great halos all around. More than that, they make it possible to control the brightness of the beams 鈥� and that could improve road safety. In wet or foggy conditions, bright lights cause glare that can impair drivers鈥� vision. Reducing it would improve safety.
鈥淛ust as advances in lighting have banished the night, they could return it to us鈥�
Parks also envisages brightly lit pedestrian crossings during the busy, dusk rush hour, but which have lights that dim as things quieten, and then turn off completely. Such advances could save cities 75 per cent of their energy use, he says 鈥� upwards of $11 billion across the US alone. In Parks鈥檚 smarter, darker world, we could save ourselves a fortune, and reclaim the sparkling riches above our heads to boot.
So let鈥檚 stop shaving darkness into an ever tinier sliver. It is time for us to let the night 鈥� and everything that slithers, flourishes and cavorts within it 鈥� grow wild once more.
This article appeared in print under the headline 鈥淭urn off the lights鈥�
