Daylighting Correlates with More Sleep in New Study

It’s well established that very high levels of daylight exposure can improve health and well-being, but few studies have explored the health effects of routine indoor exposure through windows or skylights. That was the focus of findings by Ivy Cheung and an international team of collaborators published in the journal Sleep, “Impact of Workplace Daylight Exposure on Sleep, Physical Activity, and Quality of Life.”

Measuring the effects of daylighting on 27 day-shift workers who had windows in their offices and 22 who did not, the researchers found that employees with windows got 175% more exposure to white light and slept on average 47 minutes more per night than employees who had no windows. Workers in windowless offices also reported lower vitality and higher rates of physical problems they said limited their work or other daily activities. There were no differences in age, race, gender, years at current job, or work duration between the windowed and windowless groups, but management vs. non-management positions and income levels are not discussed.

Noting the “strong association” between office windows and well-being, the researchers recommend a greater emphasis on daylight access for employees.

These findings reinforce those of a 2010 study of middle-school students by Mariana Figueiro and Mark Rea of Rensselaer Polytechnic Institute, published in Neuroendocrinology Letters. Figueiro and Rea found that blocking short-wavelength daylight from reaching the students’ eyes in the morning measurably affected their dim-light melatonin level, which in turn affects sleep cycles.