Artificial night-time light can cause great disturbance to animals and plants – even at low levels. It affects hormones and number of offspring. These are the findings of research that brings together more than 100 studies.
A team led by the University of Exeter brought together more than 100 studies and found that artificial night-time lighting has “widespread” impacts on animals and plants.
Changes to animals’ bodies and behaviour – especially hormone levels and patterns of waking and sleeping – were consistently found, according to a statement.
The study shows that levels of melatonin, a hormone that regulates sleep cycles, were reduced by exposure to artificial lighting at night in all animal species studied.
Professor Kevin Gaston, of the Environment and Sustainability Institute, said in the statement: “Particularly strong responses are seen in hormone levels, the timing of daily activity in diurnal (daytime) species, and ‘life-history’ traits such as number of offspring.
“People may imagine this is all about powerful light, but in fact we are seeing a lot of responses at quite low levels of artificial light.”
Like climate change, night-time lighting appears to benefit certain species in certain locations, but Professor Gaston said the clear message of the study was to reduce lighting where possible.
“Our study shows that we should, as a matter of principle, only use night-time lighting where we need it and no further, and at intensities that we need and no more. In effect, we need to view light like any other pollutant.
“Obviously it would be ridiculous to say ‘switch the world’s lights off’ – but we could reduce our use of light immensely with absolutely no impact on ourselves.”