If you’ve ever lived in Alaska, Denmark or Irkutsk, you are acutely aware of the differences in the amount of daylight available to you in winter months.  Many people suffer from Seasonal Affective Disorder (SAD) when days are shorter which can trigger moodiness, lethargy, even depression.  Even in the Northeast U.S. where I live, I find myself feeling less motivated when there are fewer hours of daylight to wake me up and keep me energized during the day.  Though we feel sunlight-deprivation more acutely during the winter months, our need for daylight is continuous throughout the year.  Access to natural daylight affects our productivity, our sleep and our general sense of well-being.

How much light do we need to be productive (and get better sleep)?

A good portion of our global workforce spends a larger portion of each day indoors, which essentially puts workers in a state of “light deficiency.”  We need more intense light to reset our biological clock.  Light intensity is measured in lux units, and the outdoor environment can exceed 100,000 lux in particularly sunny climates.  More typically, the illuminance level produced by an overcast sky will be around 10,000 in the winter and 30,000 on a bright overcast day in the summer. Indoors, the typical average is somewhere between 100 to 2,000 lux units — considerably less. Some sleep experts recommend being outside as much as 2 hours a day, but even going outside for 30-60 minutes during the day – say over a lunch break or walking meeting outdoors, will provide roughly 80 percent of what you need to “anchor” your circadian rhythm according to Dan Pardi, a researcher with the Psychiatry and Behavioral Sciences Department at Stanford, and the Departments of Neurology and Endocrinology at Leiden University in the Netherlands. The ideal time to go outside, in order to align our body clock, is during the morning hours up until mid-day when the sun is at its brightest, but any time during the day will help.

How can we effectively expose ourselves to more daylight during the workday?

Your work schedule, workspace and commute will best determine how you can expose yourself to daylight, but here are some ideas:

  • Walk, bike or scoot to work. Hey, you need the exercise anyway, right?
  • Sit by a window each day (as close as possible, like within 5 feet). Most glass in large buildings actually reflect the light waves that reset our biological clock so your best bet is to sit right next to the window.
  • If your primary work area is not by a window, take advantage of break areas, soft seating areas or other places in your workspace that are very close to windows, and go sit or stand in them for a period of time each day.
  • Go outside during your workday to take breaks, calls or walking meetings especially during time periods mentioned above.
  • Install circadian lighting at home and/or work.

What exactly is circadian lighting and how does it work?

If your workplace does not have windows, or even if it does, consider installing a circadian lighting system that provides appropriate light waves to trigger wakefulness.  These lighting systems do a number of things, but most importantly signal the suprachiasmatic nucleus or SCN in the eye, which is responsible for calibrating our day/night cycles.  Some new healthy building standards, like the WELL Building Standard, are giving “credits” for installing this feature.  Circadian lighting in workplaces take into account natural and artificial light, a certain intensity of light at the desktop height level, and the presence of high light levels for a certain amount of time during the day.

I recently visited Bishop O’Connell High School in Falls Church Virginia, where the administrative staff are testing circadian lighting in several classrooms.  The lighting systems and wellness study was designed by an incredibly smart team of people led by David Conrath, owner of Anthospheres, LCC, an industrial designer and “human-centric innovator” who works with architects along with the Marine Corp Shooting Teams and other secure branches to keep them alert and mission ready.  Conrath replaced the old fluorescent lightbulbs in their classroom with “biologically corrected” LED bulbs that mimic natural daylight (Lighting Science Awake & AlertTM series light fixtures) and also added Sun TunnelTM skylights (from VELUX) that draw in natural daylight from the roof.

The result was a very well lit classroom, but not overwhelmingly so.  I was amazed at how the natural and artificial light quality and color was so similar.  We took a look at classrooms without the new bulbs it looked like they were lit with kerosene lamps by comparison!  One of the engineering teachers I met has been teaching class at 7:45 a.m. in the same room at Bishop O’Connell for six years, but in the last year, with the new circadian lighting, noticed a real difference.  “My students are just more alert now.  They have no idea we’ve installed these new lights, but I have noticed they are more focused and energetic.”  Conrath has just completed a study of the Bishop O’Connell students using these spaces, and found that the students who struggled in years previous seemed to be improving the most.  The C- students improved two grade levels to B- (as a parent, this caught my interest).  The school is anxious to continue the study for two more years to continue and monitor the results.

Even if your workspace is lit at 500 lux, which is more than enough light for reading and most work tasks, it will not necessarily help with your biological clock.  The light that is important to our circadian rhythm is different from the light that is important to our visual system because of the spectral difference in the light sensitivity of our photoreceptors. According to Conrath, “Most people think that circadian lighting has to do with the color of light, but circadian light waves are invisible to us.  Special LED lights are required if we want to use them to increase our wakefulness or help us sleep.”  Many of these lighting systems have a return on investment that fall within the U.S. General Services Administration guidelines, and added benefits are still being quantified, but early results show increases in worker productivity, a higher sleep score and a reduction in SAD.

If there is one investment you make to improve the quality of your workplace, this one is probably it. Research from Jennifer Veitch, PhD, Principal Research Officer at National Research Council of Canada, and others shows that people who perceive their office lighting to be high quality rate their space as more attractive, have a more pleasant mood and show greater well-being at the end of the day.  People experiencing “good” lighting also felt that their performance was better than when they were not experiencing “good” conditions.

Can I try circadian lighting at home?

Yes!  There are several high quality LED bulbs out there that are easy for you to try out at home (or at work if you have a task light by your primary workspace and you are allowed to change the lightbulb).  Try some of these out and see if you notice a difference in your own energy levels and sleep quality.  The key is to use different bulbs to “wake up” or “work” versus get to sleep.  For example, try a “wake-up” bulb in the kitchen where you get your morning coffee or by your work desk, and a “sleep” bulb at your bedside.  If you are a shift worker, you need to turn on and off these lights differently to accommodate your work schedule.  I’m currently using LED bulbs from Lighting Science and I love them, but here are others brands you might like from this recent NY Times article.

Circadian Lighting

For more research on circadian lighting:

Dr. Joseph Mercola interview with Dan Pardi, MS, “How the Cycles of Light and Darkness Affect Your Health and Well-being”

Pechacek, C.S., Andersen, M., Lockley, S.W., “Preliminary method for prospective analysis of the circadian efficacy of daylight with applications to healthcare architecture”

Veitch, J., G. Newsham, P. Boyce, and C. Jones, “Lighting Appraisal, Well-Being and Performance in Open-Plan Offices:  A Linked Mechanisms Approach”