Context: Increasing urbanisation and the installation of new streetlights, security floodlights and outdoor ornamental lighting all contribute to growing light pollution.

• This light floods directly into the eyes of animals that are active at night and also into the skies.
• Key Facts: Some of the most light-polluted countries in the world are Singapore, Qatar, and Kuwait.

About Skyglow

• Sky glow is the brightening of the night sky, mostly over urban areas, due to the electric lights of cars, streetlamps, offices, factories, outdoor advertising, and buildings, turning night into day for people who work and play long after sunset.
• A proportion of light at night is redirected back downwards towards an earthbound observer causing ‘skyglow’.
• It is an omnipresent sheet of light across the night sky in and around cities that can block all but the very brightest stars from view.
• Sky glow occurs from both natural and human-made sources.

About Light Pollution

• It is excessive, misdirected, or obtrusive artificial (usually outdoor) light.
• Light pollution is a side effect of industrial civilization.
• Its sources include building exterior and interior lighting, advertising, commercial properties, offices, factories, streetlights, and illuminated sporting venues.
• Much outdoor lighting used at night is inefficient, overly bright, poorly targeted, improperly shielded, and, in many cases, completely unnecessary.
• This light, and the electricity used to create it, is being wasted by spilling it into the sky, rather than focusing it on to the actual objects and areas that people want illuminated.

Components of light pollution

• Glare: excessive brightness that causes visual discomfort
• Skyglow: brightening of the night sky over inhabited areas
• Light trespass: light falling where it is not intended or needed
• Clutter: bright, confusing and excessive groupings of light sources

Effects of light pollution

• Artificial light can cause great damage on natural body rhythms in both humans and animals.
• Nocturnal light interrupts sleep and confuses the circadian rhythm– the internal, twenty-four-hour clock that guides day and night activities and affects physiological processes in nearly all living organisms.
• One of these processes is the production of the hormone melatonin, which is released when it is dark and is inhibited when there is light present.
• An increased amount of light at night lowers melatonin production, which results in sleep deprivation, fatigue, headaches, stress, anxiety, and other health problems.
• Light pollution poses a serious threat in particular to nocturnal wildlife, having negative impacts on plant and animal physiology.
• It can confuse the migratory patterns of animals, alter competitive interactions of animals, change predator-prey relations, and cause physiological harm.

Solution

• The simple solution is to reduce animals’ experience of direct and indirect light pollution: turning off unnecessary lights at night.
• Where lights cannot be turned off, they can be shielded so that they do not shed light into the surrounding environment and sky.
• The International Dark-Skies Association has certified more than 130 ‘International Dark Sky Places’, where artificial lighting has been adjusted to reduce skyglow and light trespass. However, nearly all are in developed countries in the northern hemisphere.
• Less-developed regions are often both species-rich and, currently, less light-polluted, presenting an opportunity to invest in lighting solutions before animals there are seriously affected.