It makes sense that you'd be in a better mood working by the light of day rather than the light of fluorescent bulbs. But, a new study just published in the Journal of Clinical Sleep Medicine found that the benefits of a sunlit office environment are more than emotional. Researchers from the University of Illinois, Northwestern University, and the Hwa-Hsia Institute of Technology in Taipei evaluated the effect of sunlight on office workers' health by asking 49 day-shift employees — 27 in windowless workplaces, 22 in daylit workplaces — to report on their sleep duration and quality and to complete a comprehensive questionnaire that assessed their general well-being. Of these participants, 21 (10 who worked sans windows, 11 who worked near windows) also wore tracking wristbands that recorded their light exposure, activity levels, and how long they spent awake versus asleep over the course of a night.
Researchers found that employees situated near windows slept better and longer than their daylight-deprived counterparts, by both self-reported and tracker-recorded measurements: In fact, they slept a full 46 minutes longer. Windowed workers were also rated as more "vital" than windowless workers, displaying four times the level of physical activity and self-reporting a greater sense of well-being. The effects of natural light didn't end with the workweek, either: Even on the weekend, workers who sat near windows enjoyed better-quality, greater-quantity sleep than their peers.
The researchers recommend that "architectural design of office environments...place more emphasis on sufficient daylight exposure...in order to promote office workers' health and well-being." Of course, if you already find yourself stuck at a desk with no window in sight, this conclusion doesn't help. So, if you can't convince a window-adjacent colleague to trade places with you, try stepping outside throughout the day for regular breaks (and a welcome dose of Vitamin D). If your mood and sleep are really suffering, you might even consider investing in a sun lamp — by the time winter arrives, everyone will want to sit next to you.