University of Geneva scientists, working with others from England and Belgium, participated in a study that shows how the brain affects emotions in response to different kinds of light. Sophie Schwartz, from the university’s centre for neuroscience, tells Swisster about the significance of the research, which further explains seasonal affective disorder and why bright days can lift our spirits.

With winter drawing on and days getting shorter, many people who usually have normal mental health suffer from depression due to lack of sunlight, particularly in places where grey skies predominate at this time of year.

Seasonal affective disorder (SAD) is a well-known phenomenon, one that disappears on bright days when the sunshine returns, thanks to changes in the brain that have not been well understood – until now.

Researchers at the University of Geneva have concluded a study that shows how the brain responds to blue light, a part of the light spectrum that is often in short supply in the winter, particularly in northern Europe.

The research found that “blue light found in daylight has an immediate effect on the way our brain affects our emotions,” Sophie Shwartz, a neuroscientist from the university, told Swisster.

Such ambient blue light “activates a visual pathway in the brain that is not actually used for vision but for synchronizing all sorts of biological functions such as hormonal secretions and sleep-wake cycles”, Schwartz said.

“This is like a first step in the neural basis for understanding the effect of light on the brain,” she said.

The article covering this research can be found here and an abstract of the scientific article can be found here.

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Researchers at Brigham and Women’s Hospital and the Harvard Medical School compared the effects of different colored lights on alertness and performance. They found that people exposed to blue light rated themselves as less sleepy, with a quicker reaction time than those exposed to green light. They also claimed to have fewer lapses in their attention than the others.

According to the researchers light may improve “people’s health”. Dr. Steven Lockley, the lead author of the study that appears in this issue of the journal Sleep said “Subjects exposed to blue light were able to sustain a high level of alertness during the night when people usually feel most sleepy, and these results suggest that light may be a powerful countermeasure for the negative effects of fatigue for people who work at night,” according to ABC News. He is a researcher at the Brigham and Women’s Hospital’s Division of Sleep Medicine.

These findings may help those who need to maintain alertness for long periods of time. Long distance drivers, pilots, and others that must sustain long trips without stimulation may benefit form blue light.

The researchers now believe that we use our eyes to see more than just objects, but are used to detect light for other purposes. It has been known that animals use light to help set their internal clocks. The photoreceptor system is different than that used for normal vision. It has a different sensitivity to the color of light and is retained in some totally blind people.

Lockley warns that blue light can cause damage to the eye and exposure needs to be monitored, but adds “With the advent of new, more controllable lighting technologies, we can begin to develop ’smart’ lighting systems designed to maximize the beneficial effects of light for human health.”

Copyright by Dan Wilson

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