The dark side of light pollution

Having evolved to live in the dark, many animals are now exposed to light 24/7. What effect does this have on them?
24 October 2016

Interview with 

Bob Mizon, British Astronomical Association


Dead bird


There is an increasing body of evidence to suggest how light effects humans but what about animals? Kat Arney and Chris Smith explore the evidence...

Kat - Recently, an increasing body of research suggests that light is one of the key mechanisms involved in how our body clocks regulate. So having a light on signals to your body, WAKEY WAKEY and delays sleep hormones. Essentially, we're living in a permanent state of 'mini jet lag'

But it's not just any light, the colour of light is important. Norway's Mari Hysing, from Uni Health Research in Bergen studies the effect of blue light emitted from your computer screens, televisions and smartphones...

Mari - Many of these screens have quite bright light and some of the blue light might impact your hormone production or the sleep hormone, so it actually sets your clock off a little bit. So in the same sense that being outside in the morning helps your sleep, having very bright light in the evening will probably delay your sleep pattern making it harder for you to fall asleep at night.

Kat - With halogen street lamps increasingly being replaced by LED lights which emit a lot of blue light , this is a  cause for concern, especially if you happen to have one of these lights shining through your bedroom window this is because the blue light can disrupt your circadian rhythm, or body clock, as Dr John O'Neill, MRC Laboratory for Molecular Biology has argued on the show previously...

John - We know that circadian disruption as occurs during shift work for example, is really bad for you in the long terms so there's a very strong association with chronic diseases such as diabetes, neurodegenerative disorders...

Chris - Breast cancer...

John - Exactly, yes - a load of different cancer.

Chris - But this is in people, - people who can shut out the light with curtains blinds or by putting away their phone but what those who can't? I'm referring to nocturnal animals, who have spent millions of years evolving to live in the dark and are now confronted with light 24/7. What's the cost to them?

Kat - Bob Mizon is the coordinator of the British Astronomical Association's Commission for Dark Skies and he joins us from Bournemouth. Bob, we've heard about how light at night can be harmful for humans - is it the same for animals?

Bob - Verlin Klinkenberg in the National Geographic a few years ago said "that we have invaded the night as if it were an occupied country" when, in fact, nothing can be further from the truth. Every creature almost in the world has evolved for millions of years to have a day and a night and if we give them a day and a day they're certainly not going to thrive.

Kat - What sort of animals and how are they affected by this light at night?

Bob - Well most species in the world are nocturnal. It's a very good predator avoidance strategy, of course, being in the dark and the bats, moths and owls are the ones that come to mind because they're the ones we tend to see, Fish, for example, are pretty thrown by light on their water when it's supposed to be nighttime. There's a famous case about ten years ago in Stonehaven in Scotland when anglers were very put out that the fish were not rising to feed at night because the local tennis club was floodlighting their water, and the fish's feeding and foraging habits were completely disrupted. Perhaps they starved - I don't know.

Kat - I could see that would be a problem. One of the animals we do think about a lot of coming out at night is bats but here are impacts on birds as well as other flying species at night - what are some of the impacts on them?

Bob - Yes. I mean most birds - we know of a few nocturnal species but most birds are diurnal. When they migrate, they very often fly very long distances and this goes into the night. Some American and Canadian cities are now turning off lights in tall buildings because birds, for reasons still not clear, will fly straight into lit windows. It's the Fatal Light Awareness Programme, otherwise known as FLAP in Canada and America, which highlights this problem and they show on the internet where you can find pictures of literally thousands of birds that have died overnight hitting tall buildings. This is a problem indeed. Birds migrate partly by using the light cues of the stars and the moon and we really shouldn't try to overpower those cues by shining most unnecessary light. Canary Wharf at three o'clock in a morning - do all those lights really need to be on?

Kat - I think that is an issue. What sort of cost is it to the economy, and also to the environment, from keeping all these lights on all the time when maybe they don't need to be?

Bob - I've searched,  trawled through many a website trying to find the cost of light pollution and there are almost as many estimates as there are websites. But, let me give you one example: there is a website, I think it's from the Slovenian Dark Sky Association and they claim that Europe as a whole spends seven billion Euros - that's not million that's billion Euros - every year lighting up the night sky.

Kat - Wow! And presumably that's a huge amount of wasted carbon dioxide as well just going out?

Bob - It is. You know people say oh, astronomers moaning about light pollution. But it's everybody's problem because it's your council tax being thrown away. It's money and energy that we really can't afford.

Kat - So with the Commission for Dark Skies - what are you actually asking for? Should we just switch everything off and night and go back to completely living in the dark?

Bob - No, no no. Absolutely not, no. We're not crazy, we don't want people to live in medieval darkness. We want star quality lighting. We just want lights to shine where they're needed. I took a photo today of the latest new light on the wall of my community centre here in Dorset. It's a typical modern wall mounted LED floodlight; it cannot be pointed downward; it shines sideways into neighbouring houses; it shines into the night sky; it dazzles oncoming drivers and people walking to the centre. It's an anti-light, instead of revealing it conceals. This is absolutely poor lighting at it's very worst.

Kat - If you're campaigning for better lights and more sensible lighting, have you had any successes so far, are you actually getting this message through?

Bob - Yes, the Commission for Dark Skies has been in existence now for twenty-five years and we've had quite a lot of success talking to the highways agency for example. Eversince the mid-nineties, they will not put a road light in on a main road that shines up which is good. Nearly all are LED's and the only problem is they are too bright for the job and they're very blue and, as we've heard, blue is not good if live near a light.


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