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June 3, 2013 by APRIL McCARTHY
The Amount of Light In Your Workplace Is Linked To Your Sleep and Quality of Life

A strong relationship exists between workplace daylight exposure and workers’ sleep, activity and quality of life. Windows and natural lighting can make a big the difference in your health.

Compared to workers in offices without windows, those 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. 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, sleep efficiency, sleep disturbances and daytime dysfunction.

“The extent to which daylight exposure impacts office workers is remarkable,” said study co-author Ivy Cheung, a doctoral candidate in the Interdepartmental Neuroscience program at Northwestern University in Chicago, Ill.

Changes in the circadian system are considered a natural part of aging and are implicated as an underlying factor of reduced sleep quality especially in those who work in workplaces without natural lighting or those on night shifts. Routine lifestyle rhythms with light exposure may serve as a protective factor contributing to the maintenance of high-quality sleep.

Cheung's research abstract was published recently in an online supplement of the journal SLEEP, and Cheung will present the findings Tuesday, June 4, in Baltimore, Md., at SLEEP 2013, the 27th annual meeting of the Associated Professional Sleep Societies LLC.

The study group comprised 49 day-shift office workers -- 27 in windowless workplaces and 22 in workplaces with windows. Health-related quality of life was measured using the Short Form-36 (SF-36), and sleep quality was evaluated with the Pittsburgh Sleep Quality Index (PSQI). 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.

According to the authors, the architectural design of office environments should take into consideration how natural daylight exposure may contribute to employee wellness.

When comparing long sleepers, who usually slept more than nine hours a night, and short sleepers, who usually got less than six hours a night, there are general difference in light exposures during the day.

Based on several measures, including hormone levels, body temperature and sleepiness, long sleepers had a longer biological night than short sleepers. This means that there are differences in internal circadian signals which may be queued by natural light and darkness.

Those findings are reported in the January issue of the Journal of Clinical Endocrinology and Metabolism.

These differences could help account for variations in the amount people sleep. The fact that the length of the biological night seems to vary from person to person may also help explain why it is difficult to change sleep habits willfully, he added.

“Day-shift office workers’ quality of life and sleep may be improved via emphasis on light exposure and lighting levels in current offices as well as in the design of future offices,” said Cheung.

Light Therapy

You can use artificial full-spectrum lights in the morning to help reset the body clock so you can get to sleep at a more appropriate time in the evening. In the past decade, pioneering research lead by Columbia University investigator Michael Terman, Ph.D. established that the circadian rhythms that help set your sleep patterns are highly susceptible to changes in exposure to light rays -- whether from the sun or from bulbs that mimic the full-spectrum of sunlight. By exposing the eyes to specially designed full-spectrum lights (10,000 lux fluorescent bulbs) for 30 minutes in the early morning, scientists have helped people get to sleep earlier and stay asleep longer. It is thought that regular exposure to such light in the morning triggers a more advantageous nighttime release of melatonin, the hormone that governs your body clock, but the mechanisms are not fully understood. You may be more familiar with light therapy for its use in treating seasonal affective disorder (SAD), a type of depression that shows up in winter months and stems from sunlight deprivation. Studies have shown that a course of light therapy treatments can have a dramatically positive effect on both sleep and symptoms of depression.

Light therapy can truly work wonders for people who find it difficult to fall asleep before midnight and are sluggish in the morning. Rapid improvement in falling asleep earlier is often experienced after just a few days of 30 minutes of exposure to a light therapy box upon awakening in the morning (see for more information on the boxes). For people (even teenagers) with more severe insomnia, who regularly stay awake until 1:00 a.m. or longer, shifting sleep patterns can involve sensitive timing. So while the procedure can be done at home, it is a better idea to work with a sleep specialist to devise the treatment program for serious insomnia. The treatment also usually requires waking up a little earlier each morning, which takes real commitment. But if you are miserable from insomnia, it's worth trying.

On the research forefront are special dawn-simulating sleep masks with embedded lights that turn on gradually four hours before the end of sleep. One might think leaving the shades open will do the same thing, but bare windows raise the possibility that your bedroom will be flooded with ambient nighttime light, which poses its own set of problems that are conveniently the subject of the next discussion, Dark Therapy.

Dark Therapy

If exposing your eyes to light in the morning helps you fall asleep earlier and sleep longer, it should come as no surprise that blocking exposure to light at night can positively influence sleep. Scientists digging further into the sunlight-melatonin connection have discovered that the blue spectrum of light has the greatest impact on melatonin and circadian rhythms. If you are exposed to blue light late at night -- from a computer or television screen or a digital clock near your bed -- it can wreak havoc with your body clock making it harder for you to get to sleep and to get up in the morning. Keep your room pitch dark at night, covering all digital clock or DVD player readouts. Interestingly, a 2008 study from the Corvallis Psychiatric Clinic in Oregon showed that using amber-tinted glasses blocked the excitatory blue spectrum of light commonly encountered during television and computer viewing. Using amber glasses during evening screen-watching time had a significant effect in inducing and promoting a good night's sleep.

However, more research is needed to examine the maintenance of daily routines in broader populations with varying cultural backgrounds and living arrangements. Future longitudinal studies may assess whether lifestyle regularity constitutes a cause or a consequence of quality sleep patterns.

April McCarthy is a community journalist playing an active role reporting and analyzing world events to advance our health and eco-friendly initiatives.

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