Impact of windows and daylight exposure on overall health and sleep quality of office workers: a case-control pilot study

Abstract

Study objective: This research examined the impact of daylight exposure on the health of office workers from the perspective of subjective well-being and sleep quality as well as actigraphy measures of light exposure, activity, and sleep-wake patterns.

Methods: Participants (N = 49) included 27 workers working in windowless environments and 22 comparable workers in workplaces with significantly more daylight. Windowless environment is defined as one without any windows or one where workstations were far away from windows and without any exposure to daylight. Well-being of the office workers was measured by Short Form-36 (SF-36), while sleep quality was measured by Pittsburgh Sleep Quality Index (PSQI). In addition, a subset of participants (N = 21; 10 workers in windowless environments and 11 workers in workplaces with windows) had actigraphy recordings to measure light exposure, activity, and sleep-wake patterns.

Results: Workers in windowless environments reported poorer scores than their counterparts on two SF-36 dimensions--role limitation due to physical problems and vitality--as well as poorer overall sleep quality from the global PSQI score and the sleep disturbances component of the PSQI. Compared to the group without windows, workers with windows at the workplace had more light exposure during the workweek, a trend toward more physical activity, and longer sleep duration as measured by actigraphy.

Conclusions: We suggest that architectural design of office environments should place more emphasis on sufficient daylight exposure of the workers in order to promote office workers' health and well-being.

Keywords: architectural design; light exposure; office environment; quality of life; sleep quality.

Figure 1. Actigraphy measures of light exposure, total activity, and sleep time between workers in workplaces with windows (N = 11) and without windows (N = 10).

Actigraphy data collected in a subset of the office workers show that those with windows in the workplace had higher light exposure (A), more total activity (B), and longer sleep time (C) than workers without windows in the workplace. * p < 0.05, ^† p < 0.10.

Figure 2. Short Form 36 (SF-36) measures of vitality and role limitation due to physical problems between workers in workplaces with windows (N = 22) and without windows (N = 27).

Workers with windows in the workplace reported better scores on vitality (A) and role limitation due to physical problems (B) on the SF-36 compared to workers with no windows in the workplace. * p < 0.05.

Figure 3. Pittsburgh Sleep Quality Index (PSQI) measures between workers in workplaces with windows (N = 22) and without windows (N = 27).

Workers with windows in the workplace reported better overall global score on the PSQI (A) compared to workers with no windows in the workplace. The difference in global score is made up mainly of differences in sleep disturbances (B), daytime dysfunction (C), and sleep efficiency (D), with workers without windows reporting poorer scores than workers with windows on all three PSQI subscores. * p < 0.05, ^† p < 0.10.