SunStar May 06, 2021 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.