The study from Northwestern Medicine and the University of Illinois at Urbana-Champaign highlights the importance of exposure to natural light to employee health and the priority architectural designs of office environments should place on natural daylight exposure for workers.
Employees with windows in the workplace received 173 per cent more white light exposure during work hours and slept an average of 46 minutes more per night than employees who did not have the natural light exposure in the workplace.
There also was a trend for workers in offices with windows to have more physical activity than those without windows.
Workers without windows reported poorer scores than their counterparts on quality of life measures related to physical problems and vitality, as well as poorer outcomes on measures of overall sleep quality and sleep disturbances.
"There is increasing evidence that exposure to light, during the day, particularly in the morning, is beneficial to your health via its effects on mood, alertness and metabolism," said senior study author Phyllis Zee, a Northwestern Medicine neurologist and sleep specialist.
"Workers are a group at risk because they are typically indoors often without access to natural or even artificial bright light for the entire day. The study results confirm that light during the natural daylight hours has powerful effects on health," Zee said.
The study group included 49 day-shift office workers; 27 in windowless workplaces and 22 in workplaces with windows.
Health-related quality of life and sleep quality were measured with a self-reported form and sleep quality was evaluated with the Pittsburgh Sleep Quality Index (PSQI).
Light exposure, activity and sleep were measured by actigraphy in a representative subset of 21 participants; 10 in windowless workplaces and 11 in workplaces with windows.
The study was published in the Journal of Clinical Sleep Medicine.