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Natural office light boosts health

By Rosemary Ann Ogilvie

Natural light in the workplace appears to be so beneficial to our health that we can possibly expect it to be woven into work/occupational health and safety requirements in the future.

A Northwestern Medicine and the University of Illinois at Urbana-Champaign study of office workers reveals those who receive more light exposure in their workplace experience several key benefits denied to those who have less workplace light exposure:

  • Longer sleep duration
  • Improved sleep quality
  • Greater physical activity
  • Better quality of life

The study group of 49 day-shift office workers comprised 27 working in windowless workplaces, and 22 working in offices 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 (PSQI). Light exposure, activity and sleep were measured by actigraphy – a device worn on the wrist that gives measure of light exposure as well as activity and sleep – in a represenative subset of 21 participants, 10 of whom were employed in windowless offices and 11 in windowed offices.

Employees working in windowed offices received 173 percent more white light exposure during working hours, slept an average of 46 minutes more per night, and tended to have more physical activity compared with workers in offices with no natural light exposure. The latter had lower scores 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.

Daytime light exposure impacts mood, alertness and metabolism

Phyllis Zee, M.D., a Northerwestern Medicine neurologist and sleep specialist, and senior author of the study, pointed out in an article penned by Marla Paul that there is increasing evidence that exposure to light during the day – and especially in the morning – benefits health through its impacts on mood, alertness and metabolism. Workers are at risk, she added, because they’re typically indoors for the entire day, often lacking access to natural or even artificial bright light. “The study results confirm that light during the natural daylight hours has powerful effects on health,” says Zee.

“Light is the most important synchronising agent for the brain and body,” explains Ivy Cheung, co-lead author and Ph.D. candidate in neuroscience in Zee’s lab at Northwestern. “Proper synchronisation of internal biological rhythms with the earth’s daily rotation has been shown to be essential for health.”

Cheung says people who receive more light exposure during the day may sleep better at night, which can also help improve health. Poor sleep, insufficient sleep, and sleep deprivation are increasingly being implicated as a factor in the development of a number of health conditions.

Co-lead author, Mohamed Boubekri, an associate professor of architecture at the University of Illinois at Urbana-Champaign, commented that architects need to be aware of the importance of natural light – not only in terms of potential energy savings, but also in terms of affecting occupants’ health.

Boubekri suggests a simple design solution to augment natural light penetration in offices is to position workstations within six to seven metres of the peripheral walls containing the windows, as daylight from side windows almost vanishes outside this distance.

Written for the Australian Traditional Medicine Society (ATMS) by Rosemary Ann Ogilvie.

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Rosemary Ann Ogilvie