Ethics and Fallacies of Human-Centric Lighting and Artificial Light at Night

Human-centered design is a problem-solving approach that focuses on people first—their productivity, comfort, and user experience. A bicycle should be designed with pedals, seat, handlebars, brakes, and gear shifters in ergonomically comfortable positions. The hardware and software that comprise tablets and cellular devices should intuitively enable a positive user experience. Placing humans first is a sensible approach in many design scenarios, especially when the device or technology will not substantially interact with non-human life.

With lighting, however, human-centricity may come with collateral damage. Through Earth’s web of life, we rely on other forms of life for our own survival. As apex predators, humans consume all kinds of plants and animals, which themselves are part of wider and interconnected ecosystems consisting of all manner of biotic and abiotic components. Regrettably and incontrovertibly, some lighting designed to support a subset of human needs causes unintended negative effects on human life, and even worse consequences to non-human life. Artificial light at night (ALAN) is offered as a case in point.

Notwithstanding some practical and aesthetic benefits, ALAN exerts direct negative effects on people. The human body tells time by observing nature’s rhythm of light and dark. Electric lighting that is asynchronous with natural cycles of day and night may interfere with our natural biological clocks, thus impairing human functioning on timescales of days, weeks, and years. Simultaneously, ALAN disrupts natural ecosystems.

Flora and fauna rely on Earth’s predictable patterns of day and night to regulate life-sustaining behaviors such as sleep, eating, reproduction, and hiding from predators. ALAN disrupts those behaviors. Some species gain a short-term advantage at the expense of other species, thus disrupting ecosystems. These disturbances may not show immediate or obvious effects on humans, but this is more reflective of the inability of human science to predict, detect, and measure such effects. On timescales of decades and generations, we should expect the consequences to come back to us.

Holistic consideration of human-centric lighting should look beyond short-term effects of light on human visual, emotional, behavioral, and biological outcomes. While ethical considerations related to conserving habitats for turtles, birds, insects, fishes, and reptiles are salient, this is not mere altruism. Nor is this just romanticism about the beauty of the night sky. At root is also pragmatism. It is in our self-interest to preserve the ecosystems and biodiversity that support human life, lest today’s design decisions become tomorrow’s liabilities.

How might one practice lighting if short-term considerations about human needs yield to, or better, integrate with, long-term considerations about planetary health? To what degree, if at all, should building facades and monuments be illuminated? To what degree should window shading devices be employed at night to contain light within buildings? What are appropriate ways to light pedestrian areas, sports fields, roadways, and parking facilities? To what degree can lighting curfews and time controls be employed to preserve nocturnal habitats?

Lighting professionals are obligated to consider these questions, just as they are best positioned to improve or reduce the use of ALAN—yet, perversely, using fewer lumens or declining to light an outdoor environment is often contrary to short-term interests. A manufacturer or designer may think “If I do not light this project, then someone else will, and probably worse!”. Or a design professional may point to compliance with codes or ordinances. Should short-term rationalizations like these sidestep the larger questions? The trend of ever-increasing ALAN must be curbed if the lighting professions are to be on the right side of history.

Lighting solutions that appear human-centric on an instantaneous basis cannot be considered human-centric if they erode biodiversity over time. Our future will be better served, and the lighting professions elevated, if we are guided less by satisfying immediate human needs, and more by a vision that extends humane care to future generations and to the long-term health of the ecosystems that support our health and comfort.