The central atrium of Sydney’s 1 Bligh Street provides additional natural light.

12 August 2014 — Office workers exposed to more natural light have a better quality of life, longer sleep duration, better sleep quality and engage in more physical activity than those exposed to low levels of daylighting, according to a new study out of Northwestern University and the University of Illinois in the United States.

The results provide more solid evidence of the health and productivity benefits to workers and employers of exposure to natural light in the office, and highlight the importance architectural design should place on daylighting, the study authors said.

The study, published in the Journal of Clinical Sleep Medicine, found that employees with windows in the workplace received 173 per cent more white light exposure during work hours and slept an average of 46 minutes longer each night than employees without natural light exposure. Workers with windows were also more likely to engage in more physical activity than those without windows.

Workers without windows reported poorer outcomes than their light-exposed 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.

“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,” lead study author, neurologist and sleep specialist Dr Phyllis Zee from Northwestern Medicine said.

“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.”

Co-lead author Professor Mohamed Boubekri from the University of Illinois said architects needed to be aware of the importance of natural light not only in terms of their potential energy savings but also in terms of occupant health.

He said a simple design solution to augment daylight penetration in office buildings was to make sure workstations were within six to 7.5 metres of the peripheral walls containing the windows.

“Daylight from side windows almost vanishes after 20 to 25 feet from the windows,” he said.

Ivy Cheung, co-lead author and PhD candidate in neuroscience at Northwestern said light was the most important synchronising agent for the brain and body.

“Proper synchronisation of your internal biological rhythms with the earth’s daily rotation has been shown to be essential for health,” Ms Cheung said.