The brain response associated with blue
light could help people adapt to emotional challenges more easily.
As winter approaches and the days
get shorter, your mood may get darker too. Sunlight deprivation can make people
feel lethargic, gloomy, and irritable, and for some it can lead to the
condition known as seasonal affective disorder, or winter depression.
But it's not just any
light your body craves. While daylight as a whole is beneficial, different
colors of light seem to affect the body in different ways.
Light from the green part
of the spectrum is important to the eye's visual system, for instance, while
blue light seems to primarily affect the mind, including mood.
In fact, the impact of
blue light on mood may be even greater than previously thought. According to a
new study published this week in the Proceedings of the National Academy of
Sciences, blue light may play a key role in the brain's ability to process
Though preliminary, the
results suggest that spending more time under blue-enriched light -- rather
than the white light most bulbs emit -- could help stave off bouts of the blues
and make all of us feel a bit brighter during the winter months.
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Why blue light's special
Light makes it easier to
read a book and find your way around, but it's much more important than that.
By affecting hormones such as melatonin and nutrients such as vitamin D, it
also has a big impact on the body, mind, and behavior.
"For thousands upon
thousands of generations we were hunter-gatherers, out in the daylight and
exposed to that blue sky," says neurologist George Brainard, Ph.D., the
director of the Light Research Program at Thomas Jefferson University, in
Philadelphia. "Since about a century ago, when Edison and others developed
electric lighting, we've become [a] predominantly indoor-dwelling species.
We've been removed from our natural stimulus."
Studies have shown that
blue light improves alertness and mental performance, but researchers haven't
fully understood what makes it different from red, green, or white light.
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tired to terrific
Now they're getting some
answers. In the new study, 17 healthy volunteers were placed in a dimly lit
lab, hooked up to a brain-scanning machine, and exposed to 40-second bursts of
alternating blue and green light with periods of darkness in between. As the
lights came on and off, the researchers played snippets of recorded speech that
sounded angry or neutral, as a way of provoking an emotional reaction.
When they analyzed the
brain scans, the researchers discovered that blue light, more so than the green
light, seemed to stimulate and strengthen connections between areas of the
brain involved in processing emotion and language.
"We found that if
you have an emotional stimulus processed by the brain, it is quite impressively
affected by light and wavelength composition," says the lead researcher,
Gilles Vandewalle, a brain expert at the University of Liege, in Belgium.
Emotion and mood are
related, of course, but Vandewalle and his colleagues aren't certain that the
emotional changes they saw in the study would translate into lasting effects on
mood. (The researchers did not ask the participants how they felt.)
However, they suspect
that the brain response associated with blue light may enable people to adapt
to emotional challenges more easily, which could help regulate mood over the
Health.com: Boost your mood
Can blue light fight the
"This is going to
prove to be a very important study," says Brainard, who was not involved
in the new research. He explains that the findings may ultimately help improve
light therapy, a common treatment for seasonal affective disorder.
In conventional light
therapy, patients stare closely for 30 to 45 minutes at light boxes that emit
bright white light (which comprises light from across the spectrum). The
treatment can be highly effective, improving mood within just a few days. But
this intense exposure can cause side effects, such as headaches and eyestrain,
Although previous studies
that tested different color lights in light therapy showed mixed results
overall, a 2006 study led by Brainard found that blue light is better at
relieving the symptoms of seasonal depression than red light. "By finding
the best wavelength of light, you can use lower levels and still evoke the same
response," he says.
Health.com: Using light therapy
to fight seasonal affective disorder
The study findings also
help explain how light therapy works.
"Before, we thought
that light therapy was beneficial to mood mainly through the regulation of
biological rhythms and melatonin secretions," Vandewalle says. "Here
we propose an alternative mechanism, or at least an additional one, showing
that light can also directly affect emotion."
Time for a "lighting
Using blue light in light
therapy might be a good thing, but we may also want to think about changing the
lighting in our homes and offices, says Vandewalle, pointing to previous
studies that found that people feel better, perform better, and sleep better
when working under blue-enriched light as opposed to the light given off by
While blue light
dominates outdoors, indoor lighting emits very little of it. "The first
lightbulbs produced were only able to produce a yellowish kind of light,"
Vandewalle says. "We may have just gotten used to it, leading us to prefer
the warm, yellowish light over bluish lights that generally appear more
In the northern
hemisphere, the amount of blue light people absorb tends to peak during the
summer and drop in the winter, as they spend more time indoors.
A 2009 study conducted in
England found that in the early evening hours, blue light accounted for 40
percent of the light people absorbed during the summer months and just 26
percent in the winter months.
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can sabotage your schedule
Vandewalle's findings may
open the door to new ways of thinking about lighting. Enriching indoor lighting
with more blue light could potentially have an impact on mood and energy in
everyday life, even in people who don't suffer from seasonal affective disorder
and experience only mild gloom during the winter, Brainard says.
"We ultimately need
to be thinking about a revolution in lighting," he adds. "It is in
our best interest to have not only light that's adequate for vision but light
that's also optimal for our biology and behavior. This is a very exciting
development, but it's still in its early days."
By Lynne Peeples,
October 27, 2010 1:19 p.m. EDT