If you're being woken up in the middle of the night by the flicking on and off of a sensor light triggered by a plant blowing in the wind, the chances are your neighbours are too.
And not just your human neighbours, but pretty much anything that flies, flaps, hops, crawls, swims or scurries in the vicinity.
"We're seeing the impact of light at night in different species across all life on Earth," says ecologist Theresa Jones, who heads up the Urban Light Lab at the University of Melbourne.
The impact of light pollution on migratory animals such as turtles, seabirds and moths has been well documented.
These animals use the light from the stars to guide their journey.
Sky glow from towns or industrial plants near turtle rookeries can cause turtle hatchlings to lose their way and head inland; seabirds can crash into lighthouses; and in years gone past there have been more Bogong moths trying to navigate the dangerous corridors of Parliament House in Canberra than politicians.
Bright lighting also affects the feeding patterns of some bat species, and makes them more vulnerable to predators or likely to crash into buildings.
Less obvious species such as tammar wallabies are also affected. Being kept up all night delays their breeding season so they have joeys at less productive times of the year.
Not just the sights, but the sounds of the night are changing
Along with disrupting entire ecosystems, light pollution is even affecting the sound of the night, according to research by Dr Jones' team.
If you live near bushland you'll be familiar with the melodic twitter of the willie wagtail.
"The little willie wagtail that's on your cricket fields or footy fields that wags its little tail, and flushes out insects, is a prolific nocturnal singer," Dr Jones explains.
To be specific, it's the male that makes those sweet tunes, and being kept up all night is putting him off his game so he's less likely to sing.
"Changing male singing behaviour means you're changing their ability to affect females, and that's changing their ability to have offspring."
It's not the only iconic night singer struggling to get into the groove.
The Australian black field cricket, which is responsible for the quintessential after-dark soundtrack, is singing later into the night when light is present.
"We think light is changing their development and that's having an impact on their singing behaviour," says Dr Jones, who specialises in studying invertebrates.
Changing their behaviour also affects their ability to attract the ladies.
Like us, exposure to light during night can affect the secretion of melatonin and the body clocks of many animals.
"We've got this new light pollution because we're changing all our lights to these white lights now which means we get more blue in the environment."
While LED lights are more energy efficient, they emit shorter wavelengths of light in the blue spectrum.
While most species, such as turtles and magpies, are particularly sensitive to blue light, research by Dr Jones's team shows that other species, such as swans and pigeons, have problems with warmer tones.
"That's massively problematic. We thought if we got rid of blue light then it will be fine, but that's clearly not the case."
Cumulative impact across Australia
Australia has much more dark space than other parts of the world, but this is gradually being filled in by industrial and residential development.
Conservation biologist Kellie Pendoley first started studying the impact of gas flares on turtle rookeries off the West Australian coast 30 years ago.
In the 1990s, the state government recognised that glare from flares could affect turtles and established guidelines that required companies to shield the lights so they could not be seen from the rookeries.
Today, any development that could affect endangered and migratory species, such as turtles, must conform with the Federal Government's Environmental Protection and Biodiversity Conservation Act.
There are also national light pollution guidelines for wildlife.
While individual developments may comply with these guidelines, Dr Pendoley says it is important to think about the cumulative impact of all those developments.
"Western Australia has a lot of dark areas, but that's being infilled by mining developments."
"When governments do their impact assessments they're only able to consider each facility in isolation," she says.
"But as the number of light point sources grows it does have a cumulative impact and we have to start thinking about that."
Dr Pendoley is now working on a project to measure light pollution near the turtle rookie of Mon Repos beach near Bundaberg in Queensland.
"The Queensland coast is just one big strip of light."
"You can see over time how development and residential areas just crept closer and closer [to the beaches]."
Dr Pendoley is working with the local council to measure light pollution in the area and how it changes with time using a network of sky glow sensors.
The idea of the project, which is still just getting up and running, is to educate people about how their light is visible in the sky.
"What it shows, and what's been difficult to try to get people to understand, is that measuring light in the sky is really, really complicated."
Light pollution is caused by three factors: light shining upwards and bouncing off clouds and particles in the atmosphere, direct glare, and indirect reflection off surfaces.
"You might have one light shining into the sky which you can see and it's not a big deal but if a big cloud comes overhead, all of a sudden that's a spotlight bouncing off a cloud and it just illuminates the horizon."
What can we do to make our night environment work for us and wildlife?
Our love affair with lighting started in 1888 when the regional centre of Tamworth switched on the first electric streetlights in Australia.
Today, street lighting is one of the major contributors to light pollution.
In Australia it's estimated that 30 per cent of all exterior lighting is actually wasted.
Our desire to light up our night-time environment has created a self-fulfilling cycle, says lighting expert Landon Bannister, who works with Southern Lighting in Tasmania.
"The primary issue is we see the world in contrast."
"Lighting salespeople and manufacturers are very good at selling the idea ... that you need all this light for safety reasons and you need it to be able to see."
The problem is, he says, the more we keep adding light, the more light you need to make a contrast.
"So we keep making [the problem] worse in order to improve it."
And there is no evidence brighter lighting can reduce crime, he adds.
Street lighting is owned by the energy providers, but local councils are becoming increasingly involved in the issue of light pollution.
Mr Bannister is currently working with the Glenorchy City Council on the northern outskirts of Hobart to revamp the lighting in the main street so it reduces light pollution and makes the area friendlier for both humans and wildlife.
So what does good lighting look like? There are a few basic principles.
- Directing light downwards towards the ground
- Using warm sources of light
- Shielding the light source so it doesn't produce glare
- Using light only where and when it is needed
Well designed low-level and glare-free lighting can often provide a greater sense of safety than just painting the streets with bright light, adds Adam Carey, creative director of lighting design company Eluminarti.
Mr Carey designed the first council-wide urban lighting plan in Australia for the Sunshine Coast Council, which also has turtle nesting sites along the coast.
What and how structures such as roads need to be lit is guided by two Australian standards. But he believes we are still taking a one-size fits all approach to the issue.
"There has not been a great deal of focus on a wholistic environmental approach with street lighting in Australia," he says.
One problem, he says, is the move towards LED lighting to save energy and cost.
"Unfortunately, we've focused just on the carbon reduction and not actually what the light is doing."
Astronomer Fred Watson agrees.
"This first generation of LEDs the highest efficiency ones are the ones with the greatest amount of blue light in them," Professor Watson says.
"It would have been better if councils had waited another few years until the technology matured then you get really good urban lighting."
Still, he is hopeful, that change will happen albeit it may take another 15 years.
In the meantime, though, there are things you can do in your own backyard that can help.
What you can do to reduce light pollution
"The first thing you need to ask yourself 'how much light do I need?' You want to make sure the light is for you," Mr Bannister says.
- Install lights that are angled down to the area you need to light
- Lower the height of your lights so they provide an ambient glow
- Use warm coloured lights
- Turn your solar LED lights off
- Shield lights — if your neighbour can see the point of light then your lights are too bright
- Don't use security lights all night.
- Choose sensor lights carefully. While they only come on for short periods of time, many don't shield the light very well. Think about lights that are triggered by heat not movement
The easiest tip of all is turn your light off and draw your curtains.
"It's lovely seeing the moths and flies on your window but basically what you've done is trapped them in an environment that is possibly going to kill them," Dr Jones says.
"With light pollution, you literally flick the switch and suddenly the problem disappears."