If you’ve got a garden, balcony or other outdoor space, lights are pitched as a way to add “atmosphere” and “enchantment” after dark.
Visit a garden centre and you’ll see all manner of electric, battery and solar-powered kit. There’s everything from storm lamps to waterproof outdoor candles, fairy lights with which to drape your trees and shrubs, and carnival bulbs to festoon your fences. There are pond lights, illuminated fountains, Moroccan-style lanterns, kerb lights, stake lights, light-up frogs and even lights disguised as rocks.
Outdoor lights can be functional or pretty to look at, but they might not be great for nature, says the World Economic Forum (WEF) in an article published this month.
Light and dark have the biggest influence on circadian rhythms, the article says. Before electric light, we lived, slept, and worked according to the sun. This rhythm is encoded into all living things, from people to plants, says the WEF.
This trend for lighting up gardens may seem an inviting one, but it needs to be done with care
We’ve been sold the idea that replacing instead of fixing is faster, but is it really?
How to go green for St Patrick’s Day without the environmental toll
Ireland is emerging from winter, but maybe hold off mowing your lawn for now
In the modern era, however, we are lighting our homes, gardens, offices and streets to the point where night-time light pollution, back in 2016, covered nearly 80 per cent of the planet, according to The New World Atlas of Artificial Night Sky Brightness, a paper published in Science Advances.
[ Quiet, please! The remarkable power of silence – for our bodies and our mindsOpens in new window ]
Why is this bad? Studies show that birds, bats and insects are among those in the natural world affected by light pollution.
If you have a garden, birds are disturbed from sleep in it by lighting and can begin singing there before dawn, says the Royal Horticultural Society (RHS), a British gardening charity. Robins especially seem sensitive to light and will extend their feeding period into the night where artificial light is present.
Owls may find hunting more difficult in lit, urban areas, and birds that prefer to start migration flights at night can become disorientated, the society says.
In lit areas, shorter periods of night-time darkness mean less time for foraging or hunting of dawn, dusk or nocturnal species, says the RHS.
Lighting up your garden pond leaves frogs without a place to lay their eggs. String jaunty lights in your hedges and trees, and baby chicks and moths won’t know whether it’s day or night.
If you must use lights, position them as low as possible, and aim them downwards or towards where they’re needed, says the RHS. Turn garden lights off when not in use
Under some lights, aquatic insects can mistake surfaces for water and lay their eggs there where they will fail.
Lighting up your borders isn’t great either. Scientists are increasingly concerned about the decline of insects. Bees, ants and beetles are disappearing. Their loss has far-reaching consequences for entire ecosystems. Insects provide food for many birds, frogs and bats, while plants rely on insects for pollination.
Since artificial light in gardens disrupts natural behaviour for a range of wildlife, it’s important to retain some dark areas and also question whether you really need lighting, says the RHS.
The type, or frequency, of light seems to affect species differently. As a general rule, insects are more sensitive to short-wavelength UV, blue and green light than long-wavelength orange, red and infra-red or light, says the RHS.
Dim lights, such as warm white solar-powered lights, are less likely to affect wildlife. But avoid coloured solar lights, as these seem to confuse and attract some worms, says the RHS.
If you must use lights, position them as low as possible, and aim them downwards or towards where they’re needed, says the RHS. Turn garden lights off when not in use.
[ Building houses can be compatible with the creation of new habitats for wildlifeOpens in new window ]
Choose low-intensity lighting and warmer hues (warm white, yellow or amber), it says. Solar lighting is cheap and safe, and emits a dull glow suitable for garden use, says the society.
Only put lights where you really need them, says DarkSky International. Use controls such as dimmers, timers and motion sensors to make lights efficient - this will waste less energy and less of your money. If you must use lights, use warm-coloured ones where possible, and limit the use of blue wavelength lights such as white LEDs which are believed to be the most disruptive, says DarkSky.
The trend for lighting up gardens as an extension of our living space may seem an inviting one, but it needs to be done with great care, says the RHS. A garden can be just as magical a place enjoyed in moonlight.
