Teachers and students are not supposed to be cave-dwelling creatures: Natural light is vital to their mental and physical health.
Yet 1 in 5 teachers in a nationally representative survey by the EdWeek Research Center report that the classroom they spend the majority of their time in doesn’t get any natural light. That reality has broad repercussions for their health and even their students’ academic performance. Another 20 percent of educators said they get natural light in their classrooms up to half of the school day.
On the other end of the spectrum, 39 percent of teachers say they get natural sunlight all day in their classrooms. But even those teachers may not be getting all the benefits they need from sunlight, said Mohamed Boubekri, an architecture professor at the University of Illinois at Urbana-Champaign who focuses on how buildings affect human health.
Sunlight is our primary source of vitamin D, which plays a critical role in regulating our circadian rhythms—in other words, the body’s internal 24-hour clock, said Boubekri. Blue sunlight in the morning triggers wake-up hormones like serotonin, while waning light in the afternoon and evening triggers go-to-sleep hormones like melatonin.
“My studies as well as many others have shown that we could be losing anywhere between 30 to 45 minutes of sleep per night because of not having natural light in our workplaces or in our classrooms,” he said. Boubekri says 45 minutes has pretty significant health implications.
An adequate amount of sleep is, in turn, important for mental health, with lack of sleep or poor-quality sleep linked to anxiety and depression. The circadian rhythm, meanwhile, is related to other bodily functions beyond sleep, and disrupting it can lead to several bad health effects, including digestion issues, changes in hormones, memory problems, and even slower healing from wounds.
There are also potential links between exposure to natural light and improved mental health as well as students’ academic performance—Boubekri points to the fact that “effective seasonal disorder,” a type of depression that happens during certain seasons, is higher in northern latitudes with less sunlight in the winter.
Researchers in Europe recently found that across 53 schools in a dozen countries, the larger the ratio between the size of the windows and the area of the room, the greater the positive effect on students’ grades and achievement. However, if there wasn’t proper shading and the light was too direct or bright that it caused glare, it could hurt students’ test performance, the study found.
How much natural light a teacher has in a classroom may very well be related to the age of the building. There was an era in the United States from the 1960s into the 1980s when windows were not included in the design of many school buildings, said Boubekri, because they weren’t as well-insulated as walls.
“It was not a major consideration,” he said. “In the ‘70s and even ‘80s, we were more looking at energy conservation because of the 1973 energy crisis in Europe and in North America. So, they were more paying attention to designing classrooms with electric lighting and not paying attention to this issue of health and well-being. Today, I think we design our schools better.”
As it is, 13 percent of school buildings in use in the United States date back to the 1960s, and another 21 percent were built from 1970 to 1999, according to data from a 2023 National Center for Education Statistics survey of schools.
Windows do more than let in natural light, said Boubekri. What teachers and students see outside their windows also matters.
“There is something about us being connected to the natural world that makes us feel good,” he said. “We don’t know if it’s chemical or psychological, but we feel good when we see greenery, we see trees, we see grass, as opposed to your window in a back alley overlooking another building or another brick wall.”
Research has shown that hospital patients in intensive care heal more quickly if they have windows in their rooms overlooking greenery.
‘Daylighting': How to improve the lighting in classrooms
So, what should a teacher do if their classroom has little to no natural light? The answer is “daylighting,” which means using more natural light to illuminate indoor spaces. Daylighting approaches Boubekri recommends include using lamps with full-spectrum lightbulbs or lightbulbs that have a CRI of 90 percent or more. CRI stands for Color Rendering Index. LED and fluorescent lights, while energy efficient, have low CRIs. At the very least, said Boubekri, teachers should think twice before sticking decorations or pictures over the windows they do have.
Just lessening the glare from fluorescent lights, even if it doesn’t bring in more natural light, can greatly improve the feel of a classroom, said Carey Arensberg, an SEL teacher for grades K-8 in Mobile, Ala. At best, fluorescent lighting is harsh, she said. At worst it’s infuriating when the lights are flickering.
Arensberg said it helps put students in the right mindset to learn when they walk into a classroom that’s warm and welcoming. “I really believe in making your classroom feel homey, and the lights can make a huge difference for the feel of your classroom so it doesn’t feel so stark and cold.”
To create that type of environment, Arensberg has hung pale blue and beige translucent covers over the fluorescent lights in her room and set up lamps around her classroom with bulbs that emanate a warm glow. She also once requested that the maintenance people remove the lightbulbs from the fluorescent ceiling lights above her “calm corner” where students go to calm down and get control of their emotions.
Investing in pleasant classroom lighting is as good for teachers as it is for students, Arensberg added.
Teachers should also take any opportunity they have, such as a lunch break, to go outside, Boubekri said.
Even teachers whose classrooms are flooded with natural light should make time to go outside, preferably in the morning, he said. Glass filters out crucial ultraviolet B, or UVB, rays, he said.
“Even if you have sunlight inside your classroom, you’re not getting the UVB component of sunlight that triggers photosynthesis for vitamin D production,” he said. “Therefore, you do need to go outside and get some exposure of your skin to vitamin D in the sunlight.”
In addition to recess, getting outside even for a couple of short, 5-10 minute spurts is good for students, too, he said.
And while teachers are improving the lighting in their classrooms, they should also consider adding some houseplants. Plants also help decrease stress and anxiety—and even improve students’ test scores, according to some research. There are several types of houseplants that grow in low light.
Data analysis for this article was provided by the EdWeek Research Center. Learn more about the center’s work.
