Rebekah Mullaney

Manager, Research Communications
Lighting Research Center

How does light affect health? Namely via the circadian system. The circadian system regulates internal biological cycles that repeat on a daily basis, such as digestion, the release of hormones, the control of core body temperature, and the timing of alertness and sleep. The patterns of light and dark received by our eyes are the major synchronizer of the circadian system’s master clock to our local position on Earth. Without the cues provided by these light-dark patterns, the numerous physiological and behavioral systems that help to ensure our health and wellbeing become asynchronous with each other and the environment. Research has associated such asynchrony with a number of mental and physical health problems, particularly including elevated risk for certain types of cancer. In addition to light’s synchronizing effect, light can also have an acute alerting effect, similar to that provided by a cup of coffee, at any time of day or night.

Applying LRC Research in Everyday Life

As a point-of-contact here at the Lighting Research Center (LRC) for the news media and for the general public, I’m often asked for specific recommendations on how to apply LRC research in daily life. While I can’t prescribe specific treatments, I can share a few simple ways that I have applied LRC research to improve my own health and that of my family.

In general I try to get a lot of light during the daytime. If the sky is clear and the sun is shining, I go for a walk or run in the morning before work or at lunchtime. Winter mornings here in New York can be quite dark, however, when the sun doesn’t rise until 7 a.m. or later, and on these dark mornings, electric light is especially important for entraining the circadian clock, and for that alerting effect akin to coffee or tea. I have several LED fixtures in my kitchen that provide a “robust circadian stimulus”—in other words, the lights are bright! And when my family eats breakfast there each morning, I make sure all the lights are on and at full brightness.

Throughout the day, when I’m at the office, I keep the shades open to let in the daylight, and keep my office lights on. In a series of studies funded by the U.S. General Services Administration, LRC researchers found that office workers receiving high circadian stimulus (CS) during the entire workday (8 a.m. to 5 p.m.) experienced better sleep and felt less depressed compared to those receiving low CS.

“A robust light and dark pattern is important for our health and well-being,” advises LRC Director Mariana Figueiro in this Reuters news article. “Look out a window, seek light during the day, especially during the morning; go out during lunch time.”

In the evening, my family uses warm, low-level (dim) lighting. I read books to my two children each night, and I use these bulbs to light their rooms for this calming bedtime routine. I try not to use the iPad late at night, or wake up during the night and check my phone. LRC research has shown that the intense glow from an electronic screen can significantly delay sleep. For those with a fixed wake time, this translates to fewer hours of sleep per night.

Every day we at the LRC are discovering new ways in which light can be used to address many of the critical issues of our time—from reducing depression in individuals undergoing cancer treatment to decreasing pesticide use in crops to helping premature infants in the NICU stay healthy. I’m thrilled and honored to be a part of it.

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