Issues in Interdisciplinarity 2020-21/Lights will Guide You Home: The Sociological and Environmental Impact of Light in Cities
In 2018, the UN estimated that 55% of the world's population lived in urban areas, and that number continues to increase. Urban lighting therefore affects over 3.5 billion people worldwide, as well as a significant number of animal species, and its implementation and regulation can have enormous impacts. Sociology and Ecology are two disciplines contributing to our understanding of urban lighting today. An interdisciplinary framework for these disciplines to communicate already exists: Urban Planning. However, tensions between them persist, which is reflected on lighting policies. This chapter explores the role of power in research and policies about urban lighting by identifying the conflict of priorities which impedes communication between disciplines.
Sociological priorities are manifold within the study of urban lighting, and they sometimes conflict with one another even within the same field. Three of these priorities are the reassurance of safety, gender equality and economic growth. Economic growth and the reassurance of safety have particular influence in urban lighting, while gender equality is more implicit. Sociology encourages the increase or re-design of urban lighting in order to make public space more inviting, through analysing how artificial light impacts experience.
Urban lighting and safety reassuranceEdit
Urban lighting yields latent power over individuals' emotions and perceptions of safety. The NYC Mayor’s Office conducted a study on public housing residents in New York City; only 21% of the residents felt safe at night compared to 50% during the day. This issue must be addressed by psychology experts to abate this sense of vulnerability and inability to recognise potential offenders and their facial expressions. The lack of visual clarity withdraws the potential victim’s power.
In another study, participants were shown a photograph of an urban area in different lighting levels based on varied light settings.  The photographs of lower light levels exposed much less visual information; this distorted the spatial dimension. Responses were recorded using Situation-Response Questionnaires to demonstrate that lower lighting levels and colder lights produced stronger responses of fear. Perhaps, warmer lighting can be utilised outside as academics argue it encourages a sense of calm. 
Therefore, how individuals view safety within the community is being affected by insufficient and inefficient urban lighting.
Urban lighting and gender equalityEdit
Insufficient or ill-designed street lighting is one of the main variables which can affect the gendered nature  of public space. Women and other gender minorities tend to avoid darkness, or areas that are too brightly lit, because they feel unsafe. Sometimes, this leads them to avoid going out at night altogether. Urban planners and city officials, commonly cisgender men, therefore hold latent power over gender minorities. Indirectly, their policies on urban lighting can restrict gender minorities' movements and decision-making power, influencing gender roles on a societal level (linking women to the home, for example). A UN Women report on New Delhi, where 95% of women feel unsafe, suggested that increased urban lighting would reduce gender inequalities in the city. However, the issue of gender in lighting policies is often overlooked: in London's 2018 Urban Lighting Strategy, there was no mention of it.
Urban lighting and economic growthEdit
In developing countries, urban lighting can catalyse economic growth, improve quality of life and increase wealth. Nighttime lighting and wealth are so fundamentally linked that scholars even suggest nighttime illuminations could be used to measure a country's GDP. 
Artificial light enhances productivity by allowing nighttime work. It facilitates leisure at night, encourages tourism by increasing reassurance and improving the city's aesthetic landscape. The Telegraph states roughly 1 in 7 people in the world live in "light poverty" (not having access to artificial light). Often, those who live in these conditions are forced to resort to unhealthy and dangerous alternatives to electrical light such as candles and kerosene lamps. This suggests that increases in artificial lighting in developing countries are to be welcomed.
Socio-economic arguments in favour of urban lighting can overlook the harmful ecological impacts of light pollution; 30% of all outdoor lighting is misused.  This not only results in economic loss but also contributes to climate change. For instance, in 2017, the US lost $6.3 billion and contributed an excess of 23 billion pounds of CO2.
The adverse effects of excessive city lighting transcend the common problems of energy inefficiency. The most notable "forms of light pollution are sky glow, light trespass, glare, and over-illumination".  These have severe ecological and evolutionary repercussions. The plenitude of research conducted on the topic has not obstructed it from being underestimated.
Urban lighting and wildlifeEdit
The first effects of light pollution were observed in 1888 on migratory birds, who mistake city lights for the constellations they utilise as a guide. This results in light-induced mortality, a growing anthropogenic threat that requires control.  60% of birds picked up by the Fatal Light Awareness Program (FLAP) in the Toronto region have been found dead.  Even if they survive, they have lower body weights and condition indices than fledgelings captured at the colony. Many more studies demonstrate the adverse influences on behavioural and physiological functions of various taxa. Although some outcomes are yet to be proved, the disruption of daily cycle patterns is “likely to influence processes such as growth, reproduction, eclosion, diapause, moult and embryonic development.”
Urban lighting and human healthEdit
There is additional neglect surrounding light pollution's effect on humans. Similarly to other animals, light pollution can have a strong influence on their melatonin production . As melatonin has been shown to hold antioxidant properties and boost immune responses, its lower concentrations in the body have been associated with an increased risk of cancer. Most distinctly, due to increased levels of oestrogen (also caused by suppression of melatonin production), with breast cancer. Interestingly, blue light suppresses melatonin production more than lights at longer wavelengths. Perhaps, switching to red-toned lamps could minimise these adverse health consequences.
While activists argue light pollution is a straightforward challenge, it is more complex. Viewed ecologically, the conclusion is clear: governments should introduce laws limiting illumination from the cities. Nevertheless, a reduction in urban lighting could have extreme societal repercussions. Sociology and Ecology's debate is mostly centered around "costs" and "benefits" of urban lighting , but fails to consider a middle ground. Adaptive or intelligent dynamic lighting, which adapts lighting levels according to statistics or motion sensors, is of increasing interest to researchers and provides a possible resolution. However, adaptive lighting is not well-developed, and is not even mentioned in Los Angeles' 2020-2025 lighting strategy, although LA is considered one of the most innovative cities in terms of street lighting. 
This can be attributed to a lack of well-developed connections between "research, policy and practice". Perhaps, a "collective efficacy" can be deployed towards improving awareness of urban lighting's impact on humanity and our ecological environment. Collective efficacy is the ability of individuals to control others' behaviour in a community with an intended effect. Arendt theorised that power could never be attributed to the act of a single individual, but of the group that implements, builds and stimulates the agency within the community. Informing the public would therefore encourage policy-makers to adopt street lighting that upholds sociology and ecology's conflicting priorities effectively.
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