Artificial light might be doing terrible things to our bodies
Humans have developed a generally solid best-practice guide towards sleep. When it’s light, run around and get stuff done. When it’s dark, close your eyes and recharge for the next time it’s light outside.
But technology has messed with this simple rule of thumb to the degree that we don’t really need to follow that advice anymore. If you want to work a night shift, you can light up a room enough to do so. If you want to keep reading after the natural light has gone, you don’t even need to bother with a bulb – your Kindle screen will light things up for you.
We’ve known for a while that this can mess with our sleep patterns, but a new study suggests it could be oh-so-much-worse than that, if what happens to our mousey friends is a decent parallel.
Scientists at the Leiden University Medical Center have carried out some research suggesting that all this unnatural light could be pretty harmful to us. Everything from lightbulbs to screens to street lighting may plausibly have an effect on our biology.
134 laboratory mice were exposed to constant light for 24 weeks, and the researchers found that they lost muscle and bone mass, showed signs of osteoporosis and summered from inflammation in their immune system.
If there is such a thing as good news in a piece like this, there are two things to draw comfort from. The first is that mice aren’t humans, and any direct parallels can’t be drawn without further study. To somewhat contradict the first, the second is that – in mice – the effects were reversible. “The good news is that we subsequently showed that these negative effects on health are reversible when the environmental light-dark cycle is restored,” said Johanna Meijer from Leiden University.
So that’s okay then, right? Not necessarily. Many people don’t have any control over their lighting – most obviously those working night shifts, but also people in cities with the constant glow of street lighting, as well as people in nursing homes or intensive-care units where constant light is often part of the facility.
“We used to think of light and darkness as harmless or neutral stimuli with respect to health,” said Meijer, but “we now realise this is not the case based on accumulating studies from laboratories all over the world, all pointing in the same direction.”
The next step is to do in-depth analysis on shifted light-dark cycles on the immune system, and to investigate actual health benefits on a rigid light schedule, but in the meantime, it might not hurt to invest in a decent pair of blackout curtains.
Images: Toshihiro Oimatsu and Nevalenx used under Creative Commons