These filters are supposed to protect our eyes from the harmful effects of blue light on the retina and on the circadian rhythm. In reality, they would be ineffective or even counterproductive.
- Blue light has a wavelength between 400 and 495 nanometers.
- It is naturally emitted by the sun, but also by screens.
- Several studies have shown that blue light filters have no effect in reducing retinal pathologies.
They dress our glasses, settle on the screens of our computers, smartphones and other tablets: blue light filters are more and more widespread. According to the companies that market them, they make it possible to fight against the harmful effects of the light emitted by our screens. In an article published on The ConversationConchi Lillo, a researcher from the University of Salamanca in Spain, explains that they could be counterproductive.
The hard-to-prove effects of blue light
Our circadian rhythm, or our biological clock, is conditioned by light. When we get ready to sleep, receiving blue light prevents the production of melatonin, a hormone that promotes sleep. This is the theory behind blue light filters: by preventing this light from reaching our eyes, they would allow us to continue using our screens, without affecting our sleep. For Conchi Lillo, this causal link seems too quickly established. “Most studies in this area are not representative of our average exposure to blue light, he explains. Indeed, most of the experimental conditions do not correspond to the daily life of an average person. And even then, the changes in sleep quality remain quite minimal (10-minute differences in falling asleep)”. Moreover, he points out that these studies are generally carried out with a small number of participants, often less than twenty, who are almost always men.
Are blue light filters really useful?
The Spanish scientist recalls that studies do not confirm the beneficial effects of these filters on our sleep. Especially since the light from the screens is probably not what prevents us from sleeping: “it’s not so much the excess blue light, which studies show isn’t powerful enough to seriously disrupt our circadian cycle, as what we do with our screens that keeps us from falling asleep.”, explains the author. In addition, blue light filters can have a counterproductive effect. If the use of screens is reasoned, blue light is necessary, it transmits information that allows us to regulate our circadian rhythm. “When we use too many filters, the information our brain receives is confused. On the one hand, the external stimuli tell our biological clock that we still need to be awake…But on the other hand, by completely suppressing the blue light information, the melatonin cycle is activated as if we were asleep”, details the Spanish researcher. This configuration actually disrupts the circadian rhythm, and can therefore disrupt sleep. If you have trouble sleeping and you suspect your phone to be responsible for it, it is better to stop using it at night, rather than investing in filters that are a priori ineffective!
.