Embracing the Dark: Restoring the night to save energy, preserve biodiversity and protect human health

by  Plymouth State University Environmental Science and Policy students Andrew Bell, Charley Blair, Jacob Dillon, Dylan Fabiano, Loe Hallagan, Ryley Haskins, Isla Lyons,Leah Newman, Shelby Normand, Josh Reynolds, Isabelle Schena, and Professor Rachelle Lyons.

March 2023

When you step outside and look up at the night sky, what do you see? Do you see stars, planets, and distant galaxies glimmering in the night sky? Maybe you see the growing number of satellites orbiting the Earth. Or, maybe you see an orange glow obscuring all but the Moon. In many locations, starlight is washed out by the ubiquitous glow of electric lighting.

For most of Earth’s history, there have been stable and predictable periods of night and day. It wasn’t until the widespread adoption of the light bulb that we saw the illumination of the landscape and a rapid shift in patterns of light and dark. Unless we’ve been lucky enough to travel to a dark sky reserve, such as the Maine Wood International Dark Sky Park, most of us haven’t ever experienced truly dark skies. Even rural New Hampshire has been losing the richness of its dark skies thanks to artificial light at night (ALN).

ALN is about more than losing sight of stars, poor lighting wastes energy, disrupts wildlife, and harms human health. And the environmental impacts that come with ALN have been steadily intensifying. Unwanted, unnecessary, or obtrusive electric illumination, is an under-recognized source of pollution. Without thoughtful intervention and community action, light pollution is likely to get worse. But, this story has a bright spot, we can adopt smart lighting practices today to reduce light pollution, in some cases with just the flick of a switch.

To understand light pollution we have to consider the invention of the incandescent light bulb. In the late 1800’s Thomas Edison patented, popularized, and commercialized the incandescent light bulb. This freed people from the limitations of ‘days end’, making it possible to extend the day’s activity under electric illumination. Soon electric generation, previously limited to urban areas, expanded with the Rural Electrification Act of 1936. Electrification of the rural landscape provided opportunities for electric refrigeration, telecommunications, and illumination that changed the ways we lived, worked, played, and rested.

It was not until the 1970s, as residual glow of cityscapes began to gain attention from astronomers for disrupting sky observations, that we began to consider bothersome light as pollution. Streetlights, commerce centers, vehicle lights, traffic signals, advertising, porch lights, stadium illumination all contribute to the loss of darkness. Light pollution can be classified into five types: glare, light trespass, skyglow, over-illumination, and clutter. Glare is caused by unshielded light, allowing light to go in all directions. Light trespass imposes unwanted light on an abutter’s property. The Strip in Las Vegas is a well-recognized example of clutter, but we can see clutter on just about any main street. Collectively all this light creates a diffuse and inescapable cloud of artificial illumination known as sky glow.

Ecological Impacts

Before ALN, there was sunlight during the day and darkness at night. The entire ecological world used these passings of light and dark as an internal clock to guide breeding periods, migration, foraging and feeding, growth and resting patterns for millions of years. Night skies and periods of darkness have been altered dramatically and from an evolutionary standpoint, at a lightning-quick pace. The rapid increase in light pollution is ecologically devastating. 

Populations of insects, turtles, birds, amphibians, fish, and other wildlife are negatively impacted by the rise in artificial light at night. Research shows diurnal songbirds have longer days, which leads to premature breeding (Florida Fish and Wildlife Conservation Commission, 2023). During migration, birds that rely on darkness become disorientated by bright city lights, resulting in exhaustion from flying too long or calling out to other birds, and death from hitting buildings (Audubon, 2023). 

Mounting evidence reveals the critical importance of light-dark cycles for developmental and behavioral adaptations that support survival (such as regulation of hormones, gonadal development, reproduction,  thermoregulation, and communication) for nearly all wildlife. One source suggests  New Hampshire’s endangered Karner Blue Butterfly reproduction may be “particularly vulnerable to bright artificial lighting.” Fireflies, a much-loved part of summer evenings are faced with “potentially catastrophic outcomes” according to the Xerces Society.

Human Health Effects

Artificial lighting has significant impacts on human health. Our biological clocks are governed by the day-night cycle. Paolo Sassone-Corsi, chairman of the Pharmacology Department at the University of California, Irvine, showed that the circadian cycle controls “ten to fifteen percent of our genes,” and therefore “disruption of the circadian cycle can cause a lot of health problems.” There is a growing body of evidence linking several medical disorders including depression, insomnia, cardiovascular disease, and cancer to light pollution.

When considering health impact we need to factor in not just the presence and absence of light but the color of the light we are exposed to. According to experts at Harvard Medical School, the  blue light from LEDs.computer screens, TVs, and other electronic displays “is particularly harmful.” A 2016 American Medical Association report expressed concern about exposure to blue light from outdoor lighting and recommends shielding all light fixtures and using lighting with a warmer color.

Unfounded Fears

One of the most common concerns when proposing reduced lighting is that it might increase crime and decrease safety. Research on the link between crime and lighting is largely inclusive and warrants further study. Some studies suggest that motion-sensing lights are the best deterrent for would-be criminals, seeing as we are more likely to notice a change in our surroundings. However, several studies have shown that ALN does not improve safety or reduce crime. Poorly designed or inappropriate light fixtures can cause more harm and even reduce one’s ability to see (American Medical Association 2012, Reports of the Council on Science and Public Health, pg 21). Researchers from the Journal of Epidemiology and Community Health conducted a study where they tested roads with street lights, dimmed lights, and no lighting at all. They found that street lights do not prevent crime or car accidents. Specifically regarding car accidents, street lights can sometimes decrease visibility because of the glare. In 2000, The Chicago Alley Lighting Project found a correlation between lit alleyways and crime, stating that people felt safer in a lit area, but the light fixtures can make targets more visible to predators. 

Cost or cost savings?

Another major common rebuke is the costs of replacing or modifying light fixtures to be dark sky friendly. For example, shielding lights to direct illumination where it is needed rather than scattering light energy up into the sky, or replacing bulbs with LED lights. 

Good lighting must serve a purpose. It must be targeted where it is needed and should only be as bright as necessary. The International Dark Sky Association has five guiding principles of responsible outdoor light at night, which support energy savings, safety and preserve natural darkness.

Technological advancements allow us to have control over lights; dimmer switches and motion sensors can help reduce electricity demand while making just the right amount of light available exactly when and where it is needed. Light that is not appropriately directed, overly bright or always one adds to electricity cost, carbon emissions and light pollution. Energy efficient and responsible lighting can offer significant cost savings.

Better Lighting Policy 

A number of states have already implemented policy to decrease light pollution, including New Hampshire. The laws usually require shielded light fixtures, optimizing energy efficiency and reducing glare. Some policies limit the time certain lights can be on. ( Think of the perpetually illuminated ball field or parking lot.) New Hampshire’s  2009 policy requires that any state funds used to “install or replace permanent outdoor luminaire,” consider glare, brightness and potential for light trespass. A more robust bill proposed in 2019 paved the way for state-managed property and  municipalities to,” conserve energy consumed by outdoor lighting; to minimize light pollution and glare; and to preserve dark skies as a feature of rural character wherever practicable.” This bill also aimed to reduce the ’blueness’ of outdoor lighting. Sadly the bill did not pass.

Several New Hampshire communities have established outdoor lighting ordinances. It is worth noting that many of these ordinances were established more than a decade ago and may benefit from updating. Whether revising existing light ordinances or starting from scratch the International Dark-Sky Association (IDA) has a wealth of resources to support community efforts to preserve and restore natural darkness.

Several examples of dark sky-friendly ordinances in New Hampshire and a template for communities to write their own are included in section 3.4 of the 2008 Innovative Land Use Planning Techniques Handbook for Sustainable Development (jointly compiled by New Hampshire’s Department of Environmental Services, Association of Regional Planning Commissions, Office of Energy and Planning and Local Government Center).

More Ways to Get Involved

If you are looking for ways to get involved in the stewardship of night, opportunities abound. Consider participating in Globe at Night Citizen Science Project. Each month Globe at NIght invites citizens to report their local night sky conditions. So far over 200,000 citizen science observations from around the world have helped researchers understand Light Pollution. During the summer months consider reporting Firefly sighting the Firefly Atlas project. Or download the Dark SkyMeter app which uses your iPhone camera to measure sky brightness and contribute to a global map of sky darkness. 

Assess your own property using the Five Principles of  Responsible Outdoor Light at Night. Become a Dark Sky Advocate. Learn more about the night sky with local expert Doug Arion and the Mountain of Stars program. Or consider planning a community event to celebrate International Dark Sky Week, April 15-22, 2023.

On the bright side, there appears to be a  growing awareness of light pollution and increasing scientific knowledge of the ecological and human health impacts of artificial light at night. Responsible lighting can save energy, reduce costs, preserve biodiversity, and improve human health. While municipal, State, and Federal efforts may take time and require active champions,  each of us we can make real and immediate gains as individuals flicking a switch.