ALAN or NALAN

Lights at night can affect hatching Loggerhead Sea Turtles

Photo by Emmy Ulmschneider

By Emmy Ulmschneider, Master Gardener

We have written about the importance of creating habitat in our yards.  Part of creating a safe habitat includes providing the resources that organisms need to survive as well as limiting harmful actions.  Although we might not think about it, artificial light at night (ALAN) is a form of pollution, light pollution.  No Artificial Light At Night (NALAN) is critical to protecting the night sky and keeping our night dark.   

When I moved to Texas from a major east coast city over forty years ago, one of the things I enjoyed the most was seeing stars at night.  Now forty years later, those same stars are no longer visible; our skies are lit up at night not with stars but artificial light.  We are beginning to recognize that ALAN affects both humans and natural ecosystems.  And the effects can be seen in both our cities and rural areas.  In humans, lack of sleep is often a factor in many of our common diseases like obesity and heart disease.  For the natural life around us ALAN affects circadian rhythms, a body’s natural daily clock and sleep cycle, as well as behaviors like fireflies mating, small-scale movements such as hatchling sea turtles reaching the sea or large-scale movements like migrations.   We tend to associate migrations with birds, but migration occurs in virtually all animal groups.  Here in Texas, the iconic eastern Monarch, through three to four generations, migrates south through Texas in the fall and north through Texas in the spring.  Some of the greatest effects of ALAN are on the smallest organisms, pollinators, which sustain our food systems.  And it also affects plants, especially those that bloom at night or are pollinated by nocturnal pollinators like night flying moths or bats.  We are just beginning to understand how important limiting ALAN is to us as well as our natural ecosystems. 

So, what are some of the steps you can take to limit your light pollution?  The U.S.  Fish and Wildlife Service suggests four simple steps we can all take to dim our lights at night:

·        Keep light indoors: Use blinds, curtains or shades to stop indoor light from escaping outside.  

·        Use warmer colored light bulbs:  Choose lightbulbs which are “warm” having reddish to yellow tones.  Avoid lights which are “cool” having blue tones.  

·        Control your outdoor lights: Use motion detectors, timers, or dimmers to control when and for how long your outdoor lights stay on. 

·        Shield outdoor lights: Limit the amount of light which drifts into the sky.

Although this has already taken place, if you are interested in other beneficial steps you can take or just want to know more, you can research “Discover the Night” which was celebrated during the International Dark Sky Week April 21-28, 2025.  During the week, there were virtual sessions “to explore the wonders of the night and discover real-world solutions to protect it.”  You can join a citizen-science campaign, Globe at Night, to monitor light pollution around the world.  If you garden, another step you can take is to plant a moon garden, a garden of night blooming plants.   We featured native night bloomers in a 2021 blog post.  See:  https://www.westtexasgardening.org/blog/search/night%20bloomers

So, ALAN or NALAN?  The choice is up to you. 

If you have questions, call the AgriLife office in Odessa at 498-4071 or in Midland at 686-4700.   Additional information, and our blog for access to past articles, is available at westtexasgardening.org.  Click on “Resources.”

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Sweet Four O’Clock (Mirabilis longiflora), a night bloomer

Photos by Emmy Ulmschneider