As I was driving to New Zealand's largest biomedical conference in Queenstown to present our most recent findings about our body clock and its influence on human health, I was shocked by recently installed countless very bright LED street lights.
This was on State Highway 6, in a non-residential area between Arrowtown and Queenstown. It was exactly this spot where I stopped 14 years ago during my first visit to New Zealand, when I was blown away by the immaculate beauty of the southern sky.
I had never seen this sky before (I was born in Germany), and 99% of those who live in the United States and Europe live under skies so blotted with artificial light that they cannot see the Milky Way.
When I stopped this last time near Frankton, I could not even see stars. Such changes made me wonder how long the natural beauty of the night sky, that most of us are still able to enjoy, at least in the rural South Island, can be preserved.
I am a neuroscientist and zoologist working on the effects of the circadian clock, a precise clock in our brain, on human health.
Alarmingly, rapidly growing evidence suggests that disrupting our natural rhythm which is brought about by light exposure at the wrong time may cause cancer, obesity, diabetes, depression, sleep disorders and possibly increase the risk for dementia.
This can occur due to our modern lifestyle that may include shift-work (classified as a carcinogen in Denmark), frequent jet lag, or social jet lag (the difference in the time we sleep during work and work-free days). The most concerning, rapidly increasing disruption to the circadian rhythm, is brought about by the relatively recent rapid spread of the LED technology.
Particularly blue enriched light sources like computer screens or smartphones are able to suppress the production of melatonin the hormone of the darkness. Melatonin is required to reset the clock to be accurate and is also a potent antioxidant. Microsoft and Apple have acknowledged the problem with new less-blue emitting screens or pre-installed software that filters out blue light.
Another way to reduce blue light is to use yellow-tinted glasses. While we can choose to turn off these devices in the evening and install light fittings that filter out blue light (like amber-coloured LEDs), we cannot influence the exposure to artificial light outside our homes, like the street lights.
As an undergraduate student, I worked on the body clock of insects and it is now evident that a body clock had been identified in nearly all organisms, even in the bacteria in our gut. According to one theory, it enabled the evolution of animals as it helps detoxifying oxygen in the body (hence the term antioxidant).
Have you ever wondered why insects fly around street lights? They think it is the moon and LED lights attract many more insects than the high-pressure yellow sodium light that gives Dunedin the typical yellow glow. Is this linked to the decline in insect number and diversity which is seen throughout the world with unknown consequences for our ecosystem and food sources?
I was fortunate enough to serve on the Dark Sky Advisory Board which was formed by the Dunedin City Council to communicate the pros and cons of the different new LED street lights for Dunedin, a debate that is ongoing www.odt.co.nz/news/dunedin/light-plans-progress-amid-concerns). Much more research has been done since then and the importance of this body clock was recognised by the award of the Nobel Prize for its discovery in 2017.
The Royal Society also became aware of the issue and published probably the most comprehensive information on this subject https://royalsociety.org.nz/major-issues-and-projects/blue-light-aotearoa/).
I am delighted to see a conference will be held in Tekapo on the necessity to use artificial light wisely.
While we at least talk about the problem, I received a desperate call for help from a citizen of India. According to this message, the Government is installing very bright LED lights (6500K) and the first residents are experiencing the negative effects through light spill to their homes. This could potentially affect 1.3billion people.
We are just at the beginning of an era where the high-pressure sodium lights are being replaced with LED lights of different colour temperature (from 2200K-5000K). The lower the colour temperature and lower emission of blue light, the better for our health.
These new lights will enable us to save energy but they come with risks and unknown liability issues for councils and central governments, as they last for at least one generation. It is down to us to make an informed decision now to replace these lights wisely throughout the country.
- Dr Alexander Tups is an associate professor in the department of physiology at the University of Otago.