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Blue light health benefits: For alertness and/or sleep?

Blue light may fight fatigue around the clock, says a new study. Researchers find blue light exposure may be a countermeasure for fatigue, during the day and night. Researchers from Brigham and Women's Hospital (BWH) have found that exposure to short wavelength, or blue light, during the biological day directly and immediately improves alertness and performance. These findings are published in the February 2014 issue of Sleep.

Blue light health benefits: For alertness and/or sleep?
Anne Hart, photography.

Light exposure, particularly blue light, is being recognized as a potent mean to stimulate alertness and cognition in young individuals. Aging is associated with changes in alertness regulation and cognition. Whether the effect of light on cognitive brain function changes with aging is unknown, however.

"Our previous research has shown that blue light is able to improve alertness during the night, but our new data demonstrates that these effects also extend to daytime light exposure," said Shadab Rahman, PhD, a researcher in BWH's Division of Sleep Medicine and lead author of this study, according to the February 3, 2014 news release, Blue light may fight fatigue around the clock. "These findings demonstrate that prolonged blue light exposure during the day has an an alerting effect."

You also can check out the abstracts of recent studies on the health effects of blue light, a 2014 study, "Diurnal Spectral Sensitivity of the Acute Alerting Effects of Light" and a previous study done in 2011, "Aging Reduces the Stimulating Effect of Blue Light on Cognitive Brain Functions."

In the 2011 study on aging and blue light, researchers found that the effect of blue light on brain responses diminishes with aging in areas typically involved in visual functions and in key regions for alertness regulation and higher executive processes. The researchers' findings provide the first indications that the effect of light on cognition may be reduced in healthy aging.

In the latest study, in order to determine which wavelengths of light were most effective in warding off fatigue, the Brigham and Women's Hospital (BWH) researchers teamed with George Brainard, PhD, a professor of neurology at Thomas Jefferson University, who developed the specialized light equipment used in the study. Researchers compared the effects of blue light with exposure to an equal amount of green light on alertness and performance in 16 study participants for 6.5 hours over a day. Participants then rated how sleepy they felt, had their reaction times measured and wore electrodes to assess changes in brain activity patterns during the light exposure.

The researchers found that participants exposed to blue light consistently rated themselves as less sleepy, had quicker reaction times and fewer lapses of attention during the performance tests compared to those who were exposed to green light

They also showed changes in brain activity patterns that indicated a more alert state. "These results contribute to our understanding of how light impacts the brain and open up a new range of possibilities for using light to improve human alertness, productivity and safety," explained Steven Lockley, PhD, neuroscientist at BWH and senior investigator of the study, according to the news release. "While helping to improve alertness in night workers has obvious safety benefits, day shift workers may also benefit from better quality lighting that would not only help them see better but also make them more alert."

Researchers note that the next big challenge is to figure out how to deliver better lighting. While natural light is ideal, many people do not have access to daylight in their schools, homes or work places.

In addition to improvements in daylight access, the advent of new, more controllable lighting technologies may help enable researchers to develop 'smart' lighting systems designed to maximize the beneficial effects of light for human health, productivity and safety.The National Space Biomedical Research Institute through NASA supported this research. Also, you may wish to see the abstract of another study, "Sleep Disturbances Are Related to Decreased Transmission of Blue Light to the Retina Caused by Lens Yellowing ."