We are continually bombarded with messages that warn that we are making excessive use of the screens that directly affects our vision. There are many advertisements that urge us to use filters to block the blue light from these screens before it is too late. “It will improve your rest”, “It will reduce visual fatigue caused by electronic devices”, “It will prevent eye diseases”, are some of its promises.
To what extent is it true? How Much Damage Do Digital Screens Really Do? And above all, is it true that we are damaging our sight and our rest with the blue light they emit?
Understand blue light
Artificial lighting has been a blessing for human beings, because it has allowed us to extend the duration of the days and carry out many more activities with it. Lately, much of that “extra time” is spent looking at electronic device screens, which are known to have a significant blue light component, cooler than that of classic tungsten or fluorescent bulbs.
Specifically, the range of the visible light spectrum that has a wavelength between 400-495 nanometers is known as blue light. It is a type of high energy light like violet and indigo. This type of light is produced naturally by the sun, which also contains, in proportion, other forms of light that are visible and invisible to the human eye, such as ultraviolet and infrared radiation.
Does it have any physiological implication that the light that we use most frequently during the day and at night is blue? To answer, it must be taken into account that sunlight is one of several factors that helps regulate our central biological clock, the circadian cycle. When light reaches our retina it interacts with the photoreceptors, which are what allow us to see, but also with other photosensitive cells of our retina. We refer to a group of ganglion cells that contain melanopsin, which regulate this circadian cycle.
The blue light signal prevents them from secreting melatonin, the sleep hormone (although it is not ruled out that all the light that reaches the retina influences this process). In contrast, when blue light does not reach the retina, our body secretes melatonin, easing drowsiness. From this it follows that if during that period in which we prepare to rest we expose ourselves to blue light, we will be blocking that melatonin secretion and producing a cycle dysregulation.
However, most of the work done on humans in this field has not been representative of the way the average person is exposed to blue light. That is, most of the experimental conditions do not correspond to the everyday life of the average person. And even in these experiments there were minimal changes in sleep quality (10-minute differences in falling asleep). In addition, in general they are studies with a low number of participants, in most cases less than 20 and almost always young men.
In any case, are filters the solution to the problem? Recent research indicates that blocking blue light with filters does not guarantee better quality of sleep. Admittedly, it is easy to find a culprit, blue light, put a remedy, a filter and convince ourselves that we are doing the best for our rest while we continue to use our electronic devices. But what we have to do is turn them off and go to sleep.
After all, what prevents us from falling asleep is not so much the excess blue light (which according to all accredited bodies is not powerful enough to cause a significant alteration of our circadian cycle) as what we are doing with it. Electronic device.
But there is still more. If we look at the indications of what these filters are necessary for, it turns out that many manufacturers affirm that they are necessary for everything we do in our day to day. There are even filters that warn that blue light damages our retina and contributes to the development of age-related macular degeneration, so we should avoid it completely and all the time. But the reality is that there is no scientific evidence to prove that claim. On the contrary, studies indicate that blocking blue light does not prevent or delay the development of these pathologies).
So much is the misinformation we receive that the Spanish Society of Ophthalmology has spoken out several times against these misleading advertisements, publishing various communications on its website to inform that blue light does not damage our retinas).
It should also be borne in mind that most of the work linking blue light with damage to the retina (or even neurons in the brain) has been carried out either in cultured cells or using experimental animals such as fruit flies. These conditions and experimental models do not resemble the characteristics and protection of human eyes.
In addition, the light intensity or the exposure time used in them are very different and superior to those of our electronic devices. Therefore, care must be taken when extrapolating these types of results to human physiology. And above all, avoid tabloid headlines.
Filters can be counterproductive
Despite everything we have said, many companies continue to warn of baseless exposure to blue light from our screens, taking advantage of unfounded fear to try to sell devices and filters. Which is not only unnecessary but counterproductive, since during the day we need to perceive blue light to regulate our circadian cycle. So much so that to try to alleviate the dysregulation of this cycle due to lack of daylight, what is the best treatment? Exactly: exposure to light.
Using filters, the information the brain receives is confusing. On the one hand, external stimuli tell our biological clock that we must still be awake. But by completely removing the information from the blue light, the melatonin cycle is activated as if we were asleep. And that can disrupt our circadian rhythm. In addition, removing the information from blue light without needing it impoverishes our vision.
Conclusion: if someone is worried about the quality of their sleep, the best thing to do is to put aside their mobile phone, tablet or computer for a while before going to sleep. Blue light is not to blame for our insomnia.