Who is ALAN?
Actually ALAN is Artificial Light At Night - that is street lamps, security lights, the glow from houses and shopfronts, those big floodlights used at sporting venues. ALAN is visible from space!
Why is ALAN a problem? Navigation
Many animals use light to navigate (Dung Beetles actually navigate using the Milky Way!) Many birds also navigate using the stars, as do seals. Hatching Turtles find their way to the sea using the moonlight reflecting off the waves. Sadly, artificial lights have seen them heading away from the sea and towards the roads and city lights.
A sense of timing
Light patterns offer cues for when to sleep, feed and reproduce. Even us humans are bothered by ALAN! It upsets our own circadian rhythms which tell us when to sleep. It has also been implicated in breast cancer, psychological and cardiovascular problems.
Lots of animals (and plants) are in tune with the phases of the moon. For example, coral spawning is affected by the moon phase.
It seems ALAN can also affect plants, changing flowering patterns and plant development.
Hiding from predators (and prey)
Darkness also helps animals hide. Artificial light disturbs this, for example, by helping predators to find prey or to highlight predators to prey - disrupting population balance through feeding patterns.
Wasted light
The light that can be seen from space is wasted light - it serves no useful purpose to us, so there have been some efforts to reduce the sky glow by providing better shielding and direction of lights. However this is only part of the story. Another way that light is wasted is in different parts of the electromagnetic spectrum. By and large, we use the visible part of the spectrum - our lights are to help us see. However, many lights also emit UV and, it seems, the problem may be worse with the new LED lights. This UV is generally useless for our purposes.
Sadly, as anyone who has ever used a Moth trap may know, many animals are particularly attracted to UV light. Insect species are among the worst affected, which means animals like Bats, who feed on them, also suffer.
Speaking of Bats, did you know that they are not actually blind? They are very good at seeing in low light conditions, so our artificial light can be blinding for them. Different bat species are affected to different degrees, with Pipistrelles seeming to take advantage of the insects gathered around lights, while other Bats, like our Horseshoe Bats, prefer the dark. Even though the Pipistrelles seem to be helped by the lights, it adversely affects certain insect populations, creating an imbalance.
What can we do?
Head to our Campaigns page for a chance to pledge to help with light pollution and to register for emails to keep you updated and motivated! Here are a few suggestions of ways to help:
Turning off any lights we don't need is the best thing. Consider whether you really need to light your outside space at night.
If the light is only needed occasionally, put it on as needed or carry a torch. If you light your front door or path, can you have it on a timer or switch off at the end of the day?
Security lights can be directed downwards so they are not being triggered by passers-by.
Red light is generally better than the bright white or bluish lights.
Also curtains and blinds to keep the light indoors.
You can also fit shielding around lights so they don't illuminate more than needed.
Finally, ask your local authority and highways people, your places of work, sports venues, shops and businesses to do their bit too!
Some Useful Links
Light pollution also affects our ability to enjoy the night sky, so many of the campaigns have been set up by astronomy societies
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