Until architects can incorporate some of the impossible engineering of M.C. Escher’s surreal images into their designs, large office buildings and factories can only have so many walls with windows. That leaves many workers toiling away without exposure to natural light.

While most people would prefer to have a window from which to gaze during the day, it turns out that there’s more to it than just the pleasure of a view or the status that comes with a corner office. In fact, one small case study comparing workers with windows and those without found that people who were exposed to natural light at their jobs scored significantly better in health and sleep surveys.

"We really wanted to look at some health issues related to lack of natural light in people's lives in general," Mohamed Boubekri, study leader and architectural scholar at the University of Illinois, told Co.Design.

The windowless workers scored worse on all eight components of a health survey, especially in the “vitality” area. They also showed worse sleep quality as reported on a well-established self-report sleep index.

The researchers also used a monitor to track light exposure and activity. Remarkably, they found that the workers without natural light got 46 minutes less sleep per night (on work nights) than their windowed co-workers. In addition, they didn’t perform as well in five other sleep measures, including sleep fragmentation.

And that’s not all.

Workers with windows slept better than the others on non-work nights as well, and significantly so: 8.5 hours versus 6.5 hours. The window group also got more light during times away from work, possibly because they had more energy to be active outside during their time off.

The findings, which were published in the Journal of Clinical Sleep Medicine, support the idea that exposure to daylight during the workday has benefits beyond what common sense might suggest.

“In addition to more overall light exposure, these workers sleep better, seem more active, and have higher quality-of-life ratings than those who work in artificial light all day,” writes Eric Jaffe of Co.Design. “The source of the sleep troubles, in particular, might be disruption of their circadian rhythms — the internal clocks that operate best when exposed to sufficient daylight.”

The topic of worker health in relation to daylight has not been researched extensively, although one 1997 study looked at exposure to daylight in terms of "preventive medicine" and urged designers to consider the problem in their work.

"Some say we spend 90 percent of our lives indoors," says Boubekri, who's also written a book on the role of lighting in architectural design. "It's very, very significant."

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