As the winter solstice nears and the sun disappears from the sky earlier every day, light sources become even more important to we humans. Exposure to sunlight gives us vitamin D and may have an effect on mood. The current trend of hygge, the Danish concept of embracing winter coziness, is so centred around candlelight that researchers are now warning fans about the dangers of indoor pollution given off by their dozens of tapers.
But there’s one kind of evening light issue that interests the team at DFC the most: that which beams straight into our brains from our screens. Scientists have long known that artificial “blue” light from phone, computer, and tablet screens disrupts sleep. But what they didn’t know was the precise mechanism of how this works — until a new study out of the Salk Institute shed light on it. (Sorry, couldn’t resist!)
It involves melanopsin, a protein that is created by cells in the retina when they are exposed to continuous blue light. This protein suppresses the production of melatonin, the hormone that helps us fall and stay asleep. The effects of melanopsin was believed to be dampened by the presence of proteins called arrestins, that were theorized to kick in after several seconds exposure to the light. But when the researchers experimented on mouse retinal cells, they found that there were two types of arrestins working against each other.
“In mice lacking either version of the arrestin protein (beta arrestin 1 and beta arrestin 2), the melanopsin-producing retinal cells failed to sustain their sensitivity to light under prolonged illumination. The reason, it turns out, is that arrestin helps melanopsin regenerate in the retinal cells.
‘Our study suggests the two arrestins accomplish regeneration of melanopsin in a peculiar way,’ [senior author Prof. Satchin] Panda says. ‘One arrestin does its conventional job of arresting the response, and the other helps the melanopsin protein reload its retinal light-sensing co-factor. When these two steps are done in quick succession, the cell appears to respond continuously to light.’”
Now that they know the method by which the retinal cells react to light, the researchers are looking for ways they can begin to suppress it. This would definitely help folks who stare at the ceiling at 3 AM regretting watching all those YouTube videos hours earlier. And there would be a market for photosensitive people, like migraine sufferers as well. So it seems that for those of us huddled at home this winter, in several sweaters, trying to pass the time with news reading and texting our snowbound loved ones, there might be a light at the end of the tunnel! (Sorry again!)