Researchers have identified the cells in our eyes that let light from smartphone screens disrupt sleep, cause insomnia, metabolic diseases or mood disorders.
In 10 seconds? It turns out some of the cells in our eyes play a key role in how screens disrupt our sleep. Scientists have discovered that interaction with ambient light from our phones and tablets resets our circadian clocks, which can cause all sorts of health problems. (Read the science)
So what’s new here? I mean I heard this before?Well, you are right, but now we know how your body clock and your sleep gets disrupted due to late night screen time or artificial light! This will help to design solutions to avoid disruptions to our circadian rhythms. Researchers pinpointed a type of light-sensitive cells in the retina and the proteins in them that tell our brains if it’s time to sleep. (Read the paper)
OK, so how do these cells affect the circadian clock? Well, it’s a cascade of things, but let me explain. When these cells continually sense light, they keep regenerating a protein, called melanopsin. It signals to the brain how much ambient light there is around us. If it’s darker, we’re likely to get sleepy. But, if the light is bright and melanopsin regeneration is prolonged and our circadian clock gets disturbed.
So screen light confuses these cells? Well, they just ‘think’ there is continuous bright light and trigger a reaction. More interestingly, our circadian clock normally reacts to prolonged light, but in the case of these cells, 10 minutes is enough to start cutting melatonin and the sense of sleepiness. That's bad, because our cells and organs rely on the 24-hour cycle and need sleep at regular times to tick along nicely. (More on problems due to bad sleep)
How did they found all this out? Researchers triggered melanopsin production in mice and found a complex process. They discovered the dual role of proteins, called arrestins that, along with melanopsin maintain sensitivity to light. They're responsible for “turning off” melanopsin and getting it ready to be reactivated by prolonged illumination. And when they switched off the two types of arrestins they found that the melanopsin-producing cells stopped being sensitive to prolonged light. (Read more)
So, why is it important, then? Understanding the process, researchers can work on treatments for migraines, where sufferers have a hypersensitivity to light, jet lag or insomnia. Also, research has shown that a disrupted circadian clock can lead to obesity, metabolic diseases, mood disorders and other problems. Knowing how to regulate the signals the retina relays about light can help resync circadian rhythms broken by shift work or in teenagers who don't sleep enough. (Find out more)
Even rural youth spends more time with phones than outdoors
Attachment to our digital devices has become so severe that even rural youth spends more time in front of their screens than in nature.
American researchers have surveyed 550 students living away from big cities to find out the ratio of screen time vs time spent outdoors.
The results were not surprising: they’ve found that young people were increasingly spending more time indoors and that the balance between screen time and nature shifted further towards devices for older students.
An interesting statistic was that the gap between screen time and outdoor activities was higher than average for girls, African American students and 8th graders.
Nicolas is a science journalist based in France. He completed his PhD at the University of Bordeaux specialising in mitochondria and genetics.