True or false junior answers questions about blue light and cell phone waves

Is blue light from screens dangerous for the eyes? Are phone filters useful? Neuroscience doctor Serge Picaud answers questions from students at the André Derain colleges, in Yvelines, Jules Ferry, in Essonne, and Jean Perrin, in Hauts-de-Seine.


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While the use of mobile phones was at the heart of the news this week, with the idea of ​​a “digital break” for middle school students mentioned by the Minister of National Education, The true or false junior is interested , Friday April 12, on the impact of screens on health. And in particular the light and waves they emit. Serge Picaud, director of the Vision Institute, one of the most important research centers in Europe on sight-related diseases, answers questions from students at the André Derain colleges in Yvelines and Jules Ferry in the ‘Essonne, and Jean Perrin, in Hauts-de-Seine.

No, blue light from phones is not dangerous for the eyes

“Is it true that the blue light emitted by screens is dangerous for the eyes?” asks François. “The blue light from screens is so weak that nothing, no scientific study has demonstrated the toxicity of blue light from screens, explains Serge Picaud. We know that blue light from the sun can be toxic, we have shown it. Blue light is known to be a risk factor for age-related macular degeneration (AMD).

AMD is a vision disease that appears after the age of 50 and progresses gradually. People who suffer from it are less able to distinguish objects and faces. Eventually, they can lose central vision in the retina. AMD develops in men or women whose eyes have been exposed to a lot of sunlight and who have not adequately protected them with glasses.

Yes, blue light from phones can keep us from sleeping

“Is it true that teenagers lack sleep because of blue light from screens?” Nolan asks. There are two types of blue light. On the one hand, there is blue-violet light which is toxic to the eyes, this is the one that Serge Picaud was talking about. The sun emits a lot, but cell phones very little. On the other hand, there is the turquoise blue light emitted by the sun and also by the cell phone screen. It is not dangerous for the eyes but it can prevent you from sleeping, confirms Serge Picaud.

“If we use screens that are very bright when going to bed, this turquoise blue light will activate our so-called non-visual circuits in the eye and which will activate us, which will wake us up. And this is to that’s what we often say, continues the doctor of neuroscience, when we are in jet lag abroad, at midday, we have to go out into the sun for a bit to activate these same circuits and therefore absorb a lot of this turquoise blue light which will wake us up and which will resynchronize our internal clock. This clock, if we activate it at bedtime, it will give us bad information and instead of wanting to sleep, we will on the contrary want to wake up, do other things, not to be able to sleep when, particularly if you are a teenager, you should sleep to be able to properly metabolize everything you have learned during the day.

Yes, turquoise blue light is bad for the brain

“I saw on a site that blue lights are bad for the brain. Is this true and if so what are their effects?” asks Nour

Nour is right and this is consistent with what Serge Picaud said. When we are very exposed to turquoise blue light, we produce less melatonin. However, this hormone, secreted by our brain, helps us regulate our internal clock. If we produce less melatonin, we are out of sync and have difficulty falling asleep at night. To avoid disturbing your sleep, it is best not to look at a screen before sleeping.

Yes, blue light filters can help, but less so than turning down the brightness.

“We often say that you need to activate your blue light filter, but is it really useful?” asks Antonin, intern at franceinfo. According to Serge Picaud, director of the Vision Institute, if these filters attenuate turquoise blue light, they can, in fact, be useful. On the other hand, filters that claim to protect us against the toxicity of light for our eyes are a scam. What is most effective, so as not to disrupt our internal clock, is to lower the brightness of the screen.

No, the waves emitted by cell phones are not harmful to health

“Is it true that our phone emits waves that are harmful to our health. If so, which ones and how can we avoid them?” asks Maëlys. What is true is that in order to function, a cell phone emits electromagnetic waves. When we are exposed to very high levels of magnetic waves, it can have the effect of increasing our body temperature. But, according to the National Health Security Agency (ANSES), mobile phones sold in France are very far from reaching these levels. And even if this were the case, it is not proven that this increase in temperature is harmful to health.

As for the effects of waves on the brain, there is currently no scientific evidence demonstrating a risk of cancer. The World Health Organization estimates that it will take time to assess the potential effects on people who use cell phones extensively.

In the meantime, what health authorities recommend is to use headphones when making calls or to put the phone on speaker. But hey, that’s only if it doesn’t bother your friends, your family, the people around you.

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