The Benefits of Natural Daylight on Mental Health
By Neall Digert
Sunlight, an abundant yet often overlooked resource, is crucial to human health and well-being. As the modern world increasingly embraces indoor living and working environments, Americans spend more than 90 percent of their time indoors on average. Therefore, design professionals must understand the profound impact of natural daylight on mental health.
Fortunately, each day, new research, case studies, design guides and design standards highlight the importance of daylight as a source of interior lighting that uniquely drives human health, productivity and happiness. In this article, we will delve into the myriad benefits of daylight, exploring its influence on mood, cognitive function, sleep patterns and overall mental well-being.
The science behind natural daylight and mental health
Natural daylight, a narrow yet powerful portion of wavelengths contained within the spectrum of electromagnetic radiation from the sun, positively influences various physiological processes in the human body. One of the key components of daylight is blue light, which plays a vital role in regulating the production of melatonin, a hormone responsible for sleep-wake cycles. Exposure to daylight, especially early in the day, is crucial for maintaining our circadian rhythm, which governs sleep, hormone release and other vital functions.
A review article in Sleep Medicine Reviews highlights that consistent exposure to natural daylight advances nocturnal melatonin production, improving sleep quality. Bright morning light’s phase advancement of the melatonin rhythm has proven effective in treating insomnia, premenstrual syndrome (PMS) and seasonal affective disorder (SAD). The review also links better sleep patterns to enhanced mental health, noting that sleep deprivation contributes to anxiety, depression and cognitive decline.
Additionally, the discovery of intrinsically photosensitive retinal ganglion cells (ipRGCs) and their role in the human circadian cycle and health has spurred a collaborative effort among physicians, researchers, scientists, engineers and designers to develop and apply evidence-based design. Integrating natural daylight into building design is not only an aesthetic choice but also a strategic one to promote biological health, improve sleep and enhance mental health.
This collaboration is grounded in our understanding of how ipRGCs function and affect human physiology, cognitive performance and overall well-being, combined with advances in lighting science. Modern daylighting solutions provide the tools to precisely manipulate light quality, quantity and timing. By integrating these solutions with effective human-centric architectural design, we can develop high-performance buildings that significantly enhance human health.
Mood enhancement and reduced depression
If you’ve ever spent any amount of time in a badly lit room with no natural light, you will know how draining it can feel. As living beings, we feel the benefits of being exposed to daylight, and when we don’t have it, we crave daylight and views.
This is largely due to the role of daylight in the synthesis of serotonin, a neurotransmitter that contributes to feelings of happiness and well-being. Numerous studies have shown that people who receive adequate exposure to natural daylight are less likely to experience depression and anxiety compared with those who spend most of their time indoors under artificial lighting.
However, it is important to note that simply flooding a space with as much daylight as possible is not ideal. Excessive sunlight can cause disruptive and disabling glare, as well as increase room temperatures beyond comfortable levels.
Designers must rethink the glass box and carefully manage these issues by considering the maximum and minimum light levels a room will receive and implementing shading measures or selecting light-diffusing materials to ensure a balanced and comfortable environment.
Case Study: Madison Fire Station #14
For example, a fire station is, first and foremost, a civic structure. It also doubles as a workspace, home base, gym, indoor training facility and even a public polling place. When designing Madison, Wis.’s largest fire station, the design team was tasked with addressing each of these program uses while meeting the city’s requirement for low energy use. Station #14 also had to accommodate a specific site orientation for fire trucks leaving the station, which required the main façade to face west. City engineers and the architecture team wanted to introduce a glass wall for daylighting but were concerned about controlling solar heat gain and glare.
Their solution was 2630 square feet of Kingspan Light + Air’s UniQuad® translucent wall panel system. This system allows for the controlled diffusion of natural light, mitigating glare and reducing solar heat gain. Combined with shading, glazing and canopy systems, it ensures the right amount of daylight enters the space, promoting mental well-being despite the challenging orientation.
Given that firefighters are three times more likely to die by suicide than in the line of duty and one in five struggles with behavioral health issues, access and exposure to interior daylight in the fire station may serve as a positive influence on firefighter emotional health.
Cognitive function and productivity
Daylight-filled environments not only boost mood but also enhance cognitive function and productivity. This is because when employees are fulfilled in their workplace environment, they are more engaged, produce higher-quality individual work and are much happier in general, which creates a more efficient and productive workforce.
For example, a Future Workplace poll for the Harvard Business Review surveyed 1614 North American employees and found that over a third of employees feel they don’t get enough natural daylight in their workspace. Furthermore, about 47 percent of employees admit they feel tired or very tired from the absence of natural daylight or a window at their office, and 43 percent report feeling gloomy because of the lack of daylight. The same poll found that 70 percent of people reported that access to natural daylight improved their work performance.
Additionally, a study by Cornell University found that natural daylight has been shown to decrease eye strain by 51 percent, drowsiness by 56 percent and headaches by 63 percent. Daylight even helped maintain optimal levels of alertness and focus, reducing the need for artificial stimulants like caffeine.
Case Study: Click Rain and Lemonly Headquarters
A compelling example of the transformative power of daylight in the workplace is the Click Rain and Lemonly headquarters in Sioux Falls, S.D. Originally a neglected spark plug factory built in 1919, the building was retrofitted into a modern workspace with a focus on daylighting design. This included uncovering the building’s hallmark sawtooth structure, which had been concealed beneath a lay-in ceiling and incorporating Kingspan Light + Air’s GridSpan™ translucent panel skylights. The skylights ensured abundant natural daylight throughout the large building, effectively overcoming the challenge posed by perimeter offices and meeting rooms that would otherwise block light from reaching the interior, open office space. Additionally, the translucent panels minimized glare and the potential for problematic shifting patterns of sunlight, resulting in a comfortable and visually pleasing environment for all occupants.
Case Study: Independent School District 544
These benefits are equally significant in educational environments where students spend a considerable amount of time during the most formative period of a person’s life. In fact, a study conducted by The Heschong Mahone Group found that students in naturally lit classrooms progressed 20 percent faster in math tests, 26 percent faster in reading tests and when end-of-year test scores were used as the outcome variable, students in classrooms with the most daylighting were found to have seven percent to 18 percent higher scores than those with less daylight. They also found that attendance rates (in both teachers and students) were higher than those in non-daylighted schools.
This evidence drove The Lincoln School in Fergus Falls, Minn., to incorporate a thoughtfully planned daylighting design when retrofitting a sprawling 90,000-square-foot former Target store into the new Independent School District 544 campus. Given that this big-box facility had no exterior windows, and its classrooms were situated in the interior, 49 Solatube SolaMaster Series Tubular Daylighting Devices (TDDs) were installed to capture daylight at the rooftop and channel it deep into the building’s interior. Each TDD was also equipped with a Solatube Daylight Dimmer, allowing staff to fully control the amount of daylight in each classroom for optimal comfort. By adopting this top-down daylighting approach, the district successfully transformed a windowless big-box facility into a functional educational environment with a strong focus on wellness.
Biophilic design
As society spends more time indoors, reconnecting with nature becomes increasingly critical. Biophilic design, which incorporates natural elements such as plants, water and natural daylight into built environments, offers a promising solution. A World Green Building Council report suggests that biophilic design elements can improve cognitive function, reduce stress and enhance mood and well-being.
Research supports these claims. A study by the University of Exeter found that adding plants to an office space increased productivity by 15 percent. Additionally, research published in the Journal of Physiological Anthropology indicated that plants in the office can lead to higher job satisfaction and reduced health complaints.
Designing spaces that nurture the innate human connection to nature is vital for mental and physical health. As urbanization continues to rise, biophilic design offers a way to mitigate the negative effects of spending too much time indoors, creating more harmonious and sustainable living and working conditions.
Case Study: Emery Hotel
The Emery Hotel, located in the historic Midland Bank building in Minneapolis, Minn., illustrates the possibilities of biophilic design. The hotel’s ownership aimed to revitalize and beautify the space by creating an urban oasis filled with daylight and greenery, enhancing both guest experience and employee well-being.
One significant challenge encountered during the adaptive reuse was delivering direct sunlight deep into a building surrounded by parking ramps and high-rise structures, particularly during winter when sunlight angles are low. To meet the design goals effectively, the team needed to incorporate toplighting solutions. However, traditional daylighting methods risked damaging the building’s structural integrity.
Instead, the design team installed 14 Solatube SkyVault TDDs to capture and transfer abundant daylight deep into the historic bank lobby, even on cloudy days despite the surrounding buildings. TDDs capture the daylight (whether from the sun and/or sky) from all angles through an optical dome mounted on the roof. The daylight is then transferred downward through reflective tubing and evenly distributed throughout the space using optical diffusers. Additionally, the design team equipped the TDDs with Solatube SkyVault Collector and Amplifier extensions to enhance daylight delivery, ensure consistent light levels and support plant growth.
The retrofit resulted in a lush, inviting and naturally lit space that preserved the bank’s historic elements while offering a unique environment for guests. When hotel guests and employees walk through the door, they feel as if they have been teleported to a tropical oasis, forgetting they are in the heart of downtown Minneapolis.
Conclusion
The positive impact of natural daylight on mental health is undeniable. It boosts mood, enhances cognitive function, improves sleep patterns and helps to reduce stress, making it a powerful tool that combats many mental health challenges in our fast-paced, indoor-centric world. When working on your next commercial project, whether it is a facility modernization or a clean-sheet-of-paper new design, consider making daylight the primary source of interior illumination for daytime hours! When properly done, the effective use of daylight will result in a facility that maximizes health and well-being.
For a list of the sources used in this article, please contact the editor.
Neall Digert
Neall Digert, Ph.D., MIES, is Vice President, Innovation and Market Development, at Kingspan Light + Air North America. Kingspan Light + Air is a business division of Kingspan Group PLC, the global leader in advanced insulation and building envelope solutions. The North American division of Kingspan Light + Air was established in 2016 to expand Kingspan’s vision of providing truly holistic building envelope solutions