Natural light in the office is associated with a better quality of life, according to a recent study.

Researchers from Northwestern University and the University of Illinois at Urbana-Champaign found that office workers with more light exposure at the office had longer sleep duration, better sleep quality, more physical activity and better quality of life compared to office workers with less light exposure in the workplace.

"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," Phyllis Zee, senior author of the study and a Northwestern Medicine neurologist and sleep specialist, said in a statement. "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."

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. 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.

Employees with windows in the workplace received 173 percent 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.

"Light is the most important synchronizing agent for the brain and body," said Ivy Cheung, co-lead author and Ph.D. candidate in neuroscience in Zee's lab at Northwestern. "Proper synchronization of your internal biological rhythms with the earth's daily rotation has been shown to be essential for health."

Also, people who get more light during the day may sleep better at night, which can also help improve health, Zee noted.

The findings were recently published in the Journal of Clinical Sleep Medicine.