In the last few years, increased lighting in office design has been a goal for many architectural designers and is rewarded in the form of LEED points for daylighting. Energy savings is a driving force for natural lighting in new office designs but the perks don’t end there. Studies have shown additional benefits of daylighting on workers’ psychological well-being, productivity, safety and performance. Daylighting recommendations are based on daylight factor levels between 2% and 6%. Daylight factors are a percentage of indoor luminance compared to outdoor luminance on a horizontal serve.1
Because standard office hours are during natural daylight hours office workspace lighting can have a large impact on the regulation of circadian rhythms, humans natural regulator of biological, mental and behavioral patterns. Sunlight simulation has been used for the treatment of health concerns such as depression, agitation and seasonal affective disorder. However, prior to this University of Illinois at Urbana-Champaign pilot study1 the impact lighting in the workplace has on sleep, quality of life, and overall health had not been tested.
A great deal of evidence has shown limited sleep reduces productivity and increases workplace accidents and errors. Short term memory loss, slow reflexes and reduced attention are often caused by lack of sleep. Sleep quality has also been tied to illness, mood disorders, cognitive performance and health issues such as diabetes.
The aim of this study was to examine the influence light exposure had in the workplace on workers sleep, well being and activity levels. The study compared workers in offices with daylight from glass walls, glass doors and windows to workers without direct contact with daylight from their workstations. All other variables being equal or no significant differences. Volunteers wore an Actiwatch 24 hours a day for the testing period which measured the amount and duration of light luminance during and after work hours including days off. The findings of this study suggest increased lighting in office design can raise sleep duration and sleep quality resulting in a healthier, safer, more efficient workplace.
Mental and Physical Conditions of the Two Office Worker Groups:
- average results showed better sleep quality during work night for workers with windows in their workspace than workers without daylight
- workers with windows at their workspace reported better sleep on free day nights (weekends, days off of work)
- workers in office settings without windows recorded lower scores in both physical and mental testing components than workers in offices with daylight exposure.
Summary: Increased Lighting in Office Design Improves Sleep
The results of the study indicate a relationship with workplace light exposure and workers sleep quality, activity level and quality of life. Workers with natural light in their workspaces slept an average of 46 minutes more per night during the work week than workers in workplaces without windows.
“Architects need to be aware of the importance of natural light not only in terms of their potential energy savings but also in terms of affecting occupants’ health,” says co-lead author Mohamed Boubekri, an associate professor of architecture at the University of Illinois at Urbana-Champaign.
As emphasized in the World Health Organization’s Declaration on Occupational Health for All,2 the focal point for practical occupational health activities is the workplace. Facility managers architects and interior designers dedicated to occupational health must can incorporate architectural features such as glass walls, glass doors, windows and walls with clerestory windows and sidelights, to increase natural daylight exposure and improve the physical and mental factors in the office interiors they create.
1 Impact of Windows and Daylight Exposure on Overall Health and Sleep Quality of Office Workers: A Case-Control Pilot Study http://dx.doi.org/10.5664/jcsm.3780 Mohamed Boubekri, Ph.D.1; Ivy N. Cheung, B.A.2; Kathryn J. Reid, Ph.D.2; Chia-Hui Wang1,3; Phyllis C. Zee, M.D., Ph.D., F.A.A.S.M.2 1School of Architecture, University of Illinois at Urbana-Champaign, Champaign, IL; 2Department of Neurology, Northwestern University, Chicago, IL; 3Department of Architecture, Hwa-Hsia Institute of Technology, Taipei, Taiwan2 WHO. Declaration on occupational health for all. Geneva, Switzerland: World Health Organization Office of Occupational Health, 1994.