We are just beginning to understand the human body's relationship to light and color temperature. Many studies have questioned how alterations in light impact our circadian rhythms, stress levels, sleep habits, mental health, appetite, and more.
It's important to consider these experiments in terms of who they aim to help – everyone responds to light slightly differently.
So when parents and teachers ask the lighting industry what tunability could mean for students, it's important to find data that specifically examines light use in the classroom. How can evidence-based design impact students? What questions should the lighting industry be asking about student and teacher needs? How is our current knowledge limited, and what can we do about that?
Here are three scientific studies from the last seven years, all of which specifically examine how color temperatures impact students.
Many publications, scientific and otherwise, have explored frequent smartphone use and whether or not it's bad for our health. The consensus seems to be that exposure to "blue" short wavelength light at night, (when our eyes are expecting longer wavelength light) causes poor sleep. However, scientists were quick to point out that this doesn't mean cooler temperatures are bad.
In fact, purposefully using blue light could have a positive impact on students, while restricting blue light could have a negative impact. This study explores the benefits of blue light and how our bodies naturally use the blue light of the sun early in the day for energy and circadian regulation.
Eleven 8th-grade students were instructed to wear orange-tinted glasses, which removed blue light, all day long for five days. The idea was to restrict all exposure to blue light from the sun or artificial fixtures, even in early morning and afternoon hours. When the students were tested again at the end of the week, researchers found that their melatonin onset was delayed by 30 minutes, which would theoretically shorten their sleep duration.
This is the first study to show non-laboratory evidence from the field that short wavelength light in the morning is important for circadian rhythm entrainment (regulation).
These results further reinforce that cooler temperatures are not themselves bad, but depend on the context: the time we are exposed to them. In fact, similar glasses were used in a 2015 study that measured the alerting effects of screen exposure in male teenagers. This time, the glasses were used at night, which allowed normal melatonin onset even though the teenage subjects were using screens.
Proving that cooler temperatures impact 8th grade students in particular has implications on lighting design in schools. A tunable system could ensure that short wavelength light illuminates the classroom at the time that it is most beneficial to students – especially in older classrooms with insufficient access to daylight.
This could also impact the debate over later start times. The argument has been made that moving school start times later does nothing to mitigate delayed sleep onset from circadian disruption. Tunability could help steer the conversation toward a solution by more accurately linking the time of day to light temperature exposure, no matter the schedule.
Rather than study the circadian rhythm itself, many researchers have attempted to quantify other physiological responses to circadian manipulation through light. Since our "master clock" intertwines with many other body systems, it should be possible to test many different reactions to light temperature. For students, that could mean measuring cognition, performance, motivation, memory, and concentration.
Four different classrooms, eighty-four 3rd graders in total, were exposed to two modes: lighting at 3500K and 1000 lux, or lighting at 6500K and 500 lux, while practicing oral reading fluency. The control group experienced only the 3500K setting, while the experimental group were exposed to 6500K while practicing. They were all tested at the 3500K lighting level.
Results showed that the experimental group, which had begun the year scoring lower than the control group, did better. By the end of the year, their test scores had improved at a much greater rate than the control students.
This study did show a marked improvement in students exposed to 6500K while studying, but the experiment was too inconsistent to use these results as direct evidence. The experimental group was not exposed to the same lighting while being tested. Also, their measurements on motivation and concentration yielded no meaningful data, which the researchers posit may be due to the young age of the students. Data from the entire study would be more accurate with more controlled parameters.
A similar study was performed with adults in 2016. That study exposed adult subjects to blue wavelength light for 30 minutes before they had to perform a working memory task, all while hooked up to an fMRI. The results showed that blue light activated parts of the brain that handle "cognition and mental control."
Overall, the hypothesis that blue light could improve test scores shows promise, but more accurate research is needed.
"Because lighting profoundly affects numerous levels of human functioning such as vision, circadian rhythms, mood, and cognition, its implicit effects on learning and classroom achievement cannot be dismissed.
Several studies have addressed how the quality and color of lighting can either impair or enhance students’ visual skills and, thus, academic performance.
Visual impairments alone can induce behavioral problems in students, and the level of concentration and motivation in the classroom."
"The inconsistent findings of earlier studies indicate that the effect of lighting on students’ performance is in part dependent on the research design. Previous studies have varied greatly in terms of target participants, lighting parameters, duration, and measurements. Hence, more research is needed to understand the effect of lighting in learning environments to provide unequivocal experimental evidence."
We already know that different color temperatures in ambient light are appropriate for different activities and moods. Schools are leaning toward a more fluid solution to lighting controls—what this research team calls "dynamic." Educational spaces cannot be static environments; teachers must be able to adjust the light throughout the day.
Preliminary lab study: Seventeen adults were measured using an ECG to monitor physiological arousal and performance. They were asked to read a novel while the light (stimulus) randomly fluctuated between 3500K, 5000K, and 6500K. The ECG measured their responses shortly after each period of light exposure. Results indicated that 6500K was the most arousing while 3500K was the most relaxing. These results were used to inform the next two experiments.
Three levels of lighting stimuli were applied to 4th-graders as they performed academic and social tasks. The students were asked to rate the lighting and report how much time they believe had passed in each session. The differences were not significant, which the researchers attribute to the artificial setting and short duration.
A field experiment studying the replacement of fluorescent lighting with tunable lighting. Students performed math problems for ten minutes every other day for two weeks, then rated the lighting. During the second week, the fluorescent lighting for the experimental group was switched to dynamic, tunable lighting. Test scores improved under the tunable lighting.
The paper suggests a mobile lighting control app for teachers. This app would use three different lighting presets (3500K, 5000K and 6500K at 500 lux, or "easy," "standard," and "intensive") adjusted manually during different student activities.
This paper is cited frequently for a reason. By performing three separate studies, researchers pinpointed gaps in knowledge about lighting and student performance. Experts have attempted to bridge those gaps in the past by applying data that didn't quite fit—either by using studies about adults in the workplace or by performing small, uncontrolled tests.
This study also shows that students are aware of their lighting. When researchers interviewed the 4th graders about their experience with each setting, they found that student answers aligned with the results of the study.
Educational environments offer a unique space to study lighting and cognition, since testing systems are already in place and students are already divided in relative categories.
However, educational spaces also have particular needs. Schools often do not have the time or resources to handle a complicated setup. Many classrooms are multipurpose. Teachers want light fixtures that can adjust to different activities and furniture arrangements throughout the day—and can coordinate with classroom media like screens and interactive whiteboards. Cost is also an issue. A public school often cannot afford the same lighting as a large private hospital, for example. Teachers aren't just worried about alertness and cognition; they also have to monitor behavioral issues and are often responsible for students' mental health.
Many schools are renovating, answering calls for sustainability and cost savings. This means replacing old, inefficient lighting systems with LED fixtures. For example, a school district in British Columbia is planning a research project to study the effects of their new Tunable LED fixtures on learning. The step toward Tunability in many cases is becoming smaller, especially as Tunable light engines become more affordable.
As architecture and design in general trend toward healthy, sustainable, and human-centric innovations, students will not be left behind. Including educational spaces in the Tunability conversation is an interdisciplinary effort—as it should be. Lighting manufacturers, designers and teachers are now collaborating to develop solutions for lighting and lighting controls that enhance student learning and integrate with students' changing lifestyles. This means we should all pay attention to all these studies.
We should keep asking questions and keep measuring the different lighting strategies developed to answer those questions.