Today’s teens are growing up in a digital world, immersed in screens. With the pandemic, screen time among youth is higher than ever before. Parents often ridicule their teens for scrolling on Tiktok or playing video games for hours on end, complaining that these technologies are “rotting their brains.” But how much harm are these screens actually causing?

Health experts have been increasingly concerned with the risks that prolonged screen exposure poses to eye health. Blue light, which we take in naturally through sunlight, plays a critical role in brain function, including regulating our sleep and wake cycle and aiding in memory retention. Under low levels of exposure, blue light can provide many benefits to our health. However, continual, long-term exposure to blue light from artificial sources like computer and smartphone screens elevates the risk of damage to the retina. The retina is the light-sensitive region at the back of the eye that sends signals to the brain which ultimately enable us to see. Our eyes don’t naturally block blue light well, so nearly all blue light within the visible light spectrum hits the retina. Excessive blue light exposure can cause severe vision problems such as age-related macular degeneration, a condition in which retinal damage results in blurred vision, as well as abnormal eye growths and even eye cancer. More commonly, overexposure to blue light causes eye strain and dry eye, often accompanied by headaches, blurred vision, and neck and shoulder pain; 27-35% of Americans reportedly experience eye strain symptoms after digital device use [2].

With children absorbing even more blue light from electronic devices than adults, parents have good reason to insist on screen time limits to restrict their kids’ blue light exposure. While the harmful effects of blue light emanating from screens on vision and physical well-being may be well studied, the effects of excessive screen use on the brain are still somewhat of a mystery. Surprisingly, most research into screen time’s role on adolescent brain development has been inconclusive and even contradictory.

During adolescence, the brain undergoes significant developmental changes, especially in regions involving socializing. For instance, the cognitive control and information processing systems, which are involved in emotional regulation and behavioral control, mature during the teenage years. As such, lots of recent neuroscience research has sought to understand how something as prominent in teen life as screens may alter this critical period of development. A 2021 study from Marciano et al. in Frontiers in Psychology, entitled “The Developing Brain in the Digital Era: A Scoping Review of Structural and Functional Correlates of Screen Time in Adolescence,” takes a sweeping view of 16 neuroimaging studies on screen time and adolescent brain development from the past decade. It’s among the first reviews of its kind, aiming to summarize the wide breadth of recent research into youth screen use. But with these studies varying widely, not just in their findings but also in their methods, synthesizing the results of these studies proved challenging. Marciano et al. suggest that neuroscience research into screen use and adolescent development is still new and “in urgent need of further evidence” [3].

Some studies discussed in Marciano et al. found that excessive screen use is associated with less efficient cognitive control in teens. In one study, the brain structures of 46 controls were compared against 26 15-year-old Internet addicts, teens who self-identified with criteria such as excessive time spent online, a need to use the Internet in increasing amounts to achieve satisfaction from it, failure to cut back on screen time, and Internet use adversely affecting other aspects of their life [4]. This comparative study found that Internet addicted teens had reduced connectivity among brain regions involved with attention and control inhibition. Internet addiction, similar to substance addiction, was linked with a deficiency in cognitive control [3].

However, other studies cited in Marciano et al. reported no significant difference in teen brain development correlated with screen time use. One study of over 2,500 10-year-olds found no significant association between screen time and brain tissue microstructure abnormalities detected by neuroimaging. This is consistent with many previous studies that have suggested a small or insignificant association between screen time and mental health outcomes [3].

Marciano et al. make sense of this wide discrepancy in teen screen use research findings in light of the fact that lots of these studies have been greatly limited by low-quality data. Many heavily rely on self-report methods or correlational data, and some fail to match the experimental and control groups with respect to other variables that potentially affect brain development, such as age, gender, or IQ. This makes it difficult to establish a direct causal relationship between screen use and brain development. The neuroimaging studies reviewed by Marciano et al. also often employed a wide variety of neuroimaging techniques, which makes it difficult to compare results across studies. Given the lack of systematic methodology and consistent findings in this area of neuroscience research, Marciano et al. concluded that more research is needed to better establish the nature of the relationship between screen use and brain development [3].

With screen-based activities occupying roughly 9 hours of an average American teenager’s day [1], it’s understandable that parents today are so overly concerned with the effects of this prolonged screen use. Aside from the many physical symptoms associated with excessive screen use, such as dry eye and neck pain, there is also the question of what neurological problems it potentially introduces in the developing adolescent brain. Though few strong negative correlations have been found between screen time and teen development so far, that doesn’t necessarily mean that they don’t exist. This field of research is still relatively new and underdeveloped, and more well-designed studies are critical for better understanding the true effect of screen time on adolescent development. But for now, as to whether phones are really “rotting our brains,” we still don’t know for sure.

References

1. 1. AACAP. (2020). Screen time and children. American Academy of Child and Adolescent
      Psychiatry. Retrieved from
      https://www.aacap.org/AACAP/Families_and_Youth/Facts_for_Families/FFF-Guide/Children-And-Watching-TV-054.aspx#:~:text=Children%20and%20adolescents%20spend%20a,spend%20up%20to%209%20 hours.
   2. Cultivating Health. (2022). How blue light affects your eyes, sleep, and health. UC Davis Health.Retrieved from https://health.ucdavis.edu/blog/cultivating-health/blue-light-effects-on-your-eyes-sleep-and-health/2022/08
   3. Marciano, L., Camerini, A.L., & Morese, R. (2021). The Developing Brain in the Digital Era:A Scoping Review of Structural and Functional Correlates of Screen Time in Adolescence. Front. Psychol. 12(671817). doi: 10.3389/fpsyg.2021.671817
   4. Wee, C.Y., Zhao, Z., Yap, P.T., Wu, G., Shi, F., Price, T., et al. (2014). Disrupted brain functional network in internet addiction disorder: a resting-state functional magnetic resonance imaging study. Addict Behav. 70(1-6). doi: 10.1371/journal.pone.0107306