IN THE modern world, lighting at night is a necessity. We have street lights and perimeter lights for safety and security on the road and in our homes. There are also decorative lights, neon signs and others. Apart from the moon’s light however, any illumination at night is unnatural and thus bound to have an impact on ecological systems. This was proven by several studies.

A team led by the University of Exeter brought together more than 100 studies and found "widespread" impacts of artificial night-time lighting on animals and plants. Changes to animals' bodies and behavior, especially hormone levels and patterns of waking and sleeping, were consistently found. The study shows that levels of melatonin (a hormone regulating sleep cycles) were reduced by exposure to artificial lighting at night in all animal species studied.

Nocturnal animals sleep during the day and are active at night. Light pollution radically alters their nighttime environment by turning night into day. Predators use light to hunt, and prey species use darkness as cover.

Previous studies have also shown night-time lighting has wide-ranging impacts from reducing pollination by insects to trees budding earlier in spring. It is thus recommended that night-time lighting be used only where it is needed. In effect, night light should be viewed as a pollutant.

A specific example of the effect of night time light is on fireflies. New research published in Insect Conservation and Diversity indicates that artificial light at night likely interferes with the courtship and mating of bioluminescent fireflies. For the study, investigators exposed courting pairs of fireflies to five colors of light at two intensities, and they recorded changes in the rate, brightness, and pattern of male advertisement flashes, as well as how often females responded.

All artificial light treatments significantly suppressed courtship activity, but bright amber light had the greatest impact on female receptivity. This suggests that artificial lights that are closest in color to firefly bioluminescence may be the most disruptive to firefly courtship.

Glare from artificial lights can also impact wetland habitats that are home to amphibians such as frogs and toads, whose nighttime croaking is part of the breeding ritual. Artificial lights disrupt this nocturnal activity, interfering with reproduction and reducing populations.

Sea turtles live in the ocean but hatch at night on the beach. Hatchlings find the sea by detecting the bright horizon over the ocean. Artificial lights draw them away from the ocean. In Florida alone, millions of hatchlings die this way every year.

So what can we do? First, turn off lights that aren't needed. If possible, make lights motion-activated. Next, put fixtures on lights to cover up bulbs and direct light where it is needed. A big contributor to attraction of light sources for most animals is seeing the actual bulb, as this could be mistaken as the moon or sun.