Daylight is a Drug: Windows are Crucial to Health and Well-being

By Helen Sanders

“Daylight is a drug and nature is the dispensing physician,” according to Deborah Burnett of Benya Burnett Consulting. Nature delivers daylight of the right type (color), in the right intensity (dose), at the right time to manage our mood, help us sleep better at night, manage our weight and help us ward off disease. Over millennia humans have evolved with the night and day cycle.[1]

The body’s natural processes, such as the immune, cardiovascular and metabolic systems, and the sleep-wake cycle, depend on this cycle to function properly. However, according to the U.S. Environmental Protection Agency, we now spend 90% of our time indoors, effectively isolating us from what keeps us healthy.


The ability of building occupants to view the outside environment is also important. It helps relax and re-focus eyes to the horizon. It reduces stress by satisfying our evolutionary need for safety by providing the ability to see approaching danger. Views of nature are especially important. Our interactions with nature reduce stress and irritability by increasing relaxation, while reducing our fight or flight cognitive functions. Views of greenery and water through windows have been linked to lower levels of stress for office workers compared to those without a window[2]. The presence of daylight and views is also correlated to double-digit improvements in productivity and cognitive test scores, better quality of life, vitality and sleep, reduced sick leave and staff turnover, and increased
candidate attraction[3-6].


There have been more than 50 studies demonstrating the positive influence of daylight and views in hospitals for patients, visitors and staff alike. Benefits for patients include reduced hospital stays, less pain felt and less pain medication taken, and improved outcomes. Medical staff experienced improved alertness, fewer dispensing errors, fewer sick days and higher retention.

Expert Roger Ulrich asserts “larger windows should be provided to permit more exposure to daylight and restorative nature views in patient rooms and other spaces where depression, pain and stress are problems”[7].


Daylight and views are positives for both students and teachers alike. Improvements in health and well-being, increased student and teacher attendance, higher educational achievement, improved behavior, and teacher retention have been documented [8, 9]. In one study, students with the most daylight progressed 20% and 26% faster on math and reading tests respectively, compared to their peers in the least daylit classrooms[9].

The authors stated, “Schools could be saving up to one month of instructional time for the reading and math curriculum that could be used for other areas of learning” with better daylit classrooms with quality views. A teacher commented, “When I’ve had it with the kids and I can’t answer another question, I just take a minute, look out the window at the view, and then I’m okay. I’m calm and ready to go back into the fray,” indicating the importance of windows for teacher stress reduction.

Research has shown that students in windowless classrooms are more hostile, hesitant and maladjusted, and tend to be less interested in their work.

With daylight and views being so crucial to human health, well-being, healing and learning, shouldn’t a minimum amount of fenestration be a basic health and safety requirement in our building codes?

1] For an overview of daylight and circadian rhythms see for example:

[2] Human Spaces: The Global Impact of Biophilic Design in the work place,

[3] Edwards and Torcellini, A literature review of the effects of natural light on building occupants, NREL report 30769,

[4] Heschong Mahone Group, Inc. (2003). Widows and Offices: A Study of Office Worker Performance and the Indoor Environment – CEC Pier 2003.

[5] Cheung et al. Impact of workplace daylight exposure on sleep, physical activity and quality of life, 2013

[6] I. Elzeyadi, Daylighting – Bias and Biophilia: Quantifying the Impact of Daylighting on Occupants Health, 2011,

[7] Roger Ulrich “Biophilic Theory and Research for Healthcare” in Biophilic Design, edited by Stephen Kellert, Judith Heerwagen and Martin Mador, 87-105. New York, Wiley 2008.

[8] Daylighting in Schools: Improving Student Performance and Health at a Price Schools Can Afford, NREL Report 28049,

[9] Daylighting in Schools, Heschong Mahone Group, 1999,

Helen Sanders, Ph.D, is in strategic business development for Technoform North America Inc. in Twinsburg, Ohio. Read her blog each month at

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