The Academy of Medicine took stock of the impact of the use of screens on the health of children and adolescents. She does not want to be alarmist, since she recognizes that ” After the age of three, screens prove to be a remarkable tool for training and awakening children, provided they are supervised by parents or educators, and the emphasis is placed on its interactivity and playfulness. On the other hand, she warns against abusive use, which is harmful at two levels: retinal (especially for young children), cerebral (especially for adolescents).
At the retinal level
The LEDs (light-emitting diodes) of the screens are in candela per square meter a thousand times brighter than incandescent lamps. They can thus be phototoxic to the retina.
In addition, they have an emission peak located in the blue and close to ultraviolet radiation, the deleterious effects of which are well documented. Thus, chronic exposure to LEDs induces cell damage that is particularly harmful to the macular retina (which provides fine vision, reading, writing and colored vision). It requires photoprotection by anti-UV and anti-blue light lenses, especially in children and adolescents, whose lens is very translucent.
It is particularly harmful at night: it inhibits the nocturnal regeneration of retinal photopigments contained in the photoreceptors, regeneration which should take place in total darkness.
At the cerebral level
Located in the hypothalamus, the internal clock drives cyclical biological processes lasting approximately 24 hours. The blue band of the light spectrum is the most active on this clock. During chronic exposure to light during the night, including screens (smartphones, tablets, computers), sleep-wake rhythm disorders appear in connection with a desynchronization of the internal clock.
However, many adolescents expose themselves to screens, including late at night. Thus, according to a survey by the WHO (World Health Organization), in Europe 30% of them communicate online. This results in ” late sleep, linked to an increase in vigilance generated by a delay in the phase of the clock and to an inhibition of the secretion of melatonin, involved in falling asleep. »
While the sleep needs of a teenager are estimated at around 9 hours per night. This sleep debt results in fatigue in the morning on getting up (30% of middle school students and 40% of high school students), impaired learning abilities due to reduced alertness and attention and a drop in school results (31 % judge ” stressful ” schoolwork). Mood and behavioral disorders (violence, hyperactivity) and metabolic disturbances (overweight) are also noted in connection with physical inactivity and the consumption of sugary foods, phenomena that the Academy associates with lack of sleep and misuse of screens.
« These children and adolescents thus find themselves in a state of desynchronization characterized by a dissociation in which biological time (the internal clock) and astronomical time (the watch) are dissociated from social life. This state is not compensated by sleep recovery during the weekend.
Recommendations
The Academy recommends:
- the use of protective glasses against blue light, in case of prolonged exposure to screens,
- the restriction, or even the banning of screens at night,
- the introduction into the school curriculum of raising student awareness of the risks associated with screens and the importance of sleep,
- parents’ awareness of these risks, the drop in school performance and the withdrawal of their adolescents being warning signs.