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The change in the sleeping patterns of adolescents is well documented in the scientific literature. However, the implications of screen time prior to sleeping for attention levels on the following morning add new dimensions to this field of knowledge.


In a period of pandemic, we know there is no point in encouraging a discourse demonising the usage of electronic devices (especially smartphones and tablets) by young persons. In 2020 and 2021, there was inevitable recognition of the importance of these resources for supporting learning and providing greater opportunities for social interactions. Nevertheless, the relationship between screen time and sleeping has never been positive: the utilisation of such devices is linked to interrupted and poorer quality sleep among adolescents. Two recent literature reviews, led by Mari Hysing and Lauren Hale, indicate that 90% of studies encountered a connection between the usage of screens and later sleeping times and/or reductions in the total amount of time asleep.

Currently, the usage of electronic devices is extremely common among adolescents both during the day and in the period prior to going to bed. Data from before the pandemic conveyed that three out of four American adolescents, between 15 and 17 years of age, used some type of technology in their bedrooms before going to sleep. According to a study in Portugal by Cristina Ponte and Susana Batista, the adolescent age group is that which spends most time per day on the Internet, reaching an average of four hours per day.


Disruption to the circadian rhythm

We know that the sleep-wake cycle follows a circadian rhythm that is primarily guided by the external signals issued by sunlight. When night falls, the body begins a process of preparation to produce the sleep hormone (melatonin) that naturally induces sleepiness. Nevertheless, artificial light may confuse this internal regulatory system. According to Patricia L. Turner and Martin A. Mainster, children and adolescents may be more sensitive to the effects of blue light (given off especially by smartphones) due to the fact that their eyes capture more light. Two other studies, by Milena Foerster and Michael O. Mireku, verify that sleep is affected to a greater extent when adolescents use screens in a dark room as the low lighting conditions mean that their pupils dilate and allow more blue light to enter.


The importance of the timing of screen exposure

A recent study, carried out in Brazil by Maria Luiza Cruz de Oliveira and four other researchers, finds that adolescents that excessively use screens prior to sleeping register lower levels of attention. This suggests that exposure to electronic devices at night may impact on the learning capacity immediately in the following morning. This study inquired about the usage of screens and sleeping patterns of 89 adolescents with an average age of 15 and with 51% reporting using a smartphone before sleeping on weekdays.

This group of adolescents also carried out a task to test their attention spans in the morning. While the length of screentime prior to sleeping does not seem to generate any relevant effect on the sleeping patterns reported by the adolescents, the same is not the case for morning attention spans that registers a negative impact. The study observed slower reactions times and less stable periods of attention in the morning among those reporting longer periods of exposure to screens prior to sleeping. The researchers conclude that the results may be interrelated with either sleep deprivation or poor quality sleeping time.


Biological time versus social time

Recent research published by Joseph Firth indicates that the effects of screen usage on the brain still remain difficult to decipher in keeping with the presence of complex interactions among different factors, including the quality of sleep, the type of utilisation of these devices, the levels of social interaction and physical activity. Despite this uncertainty, researchers such as Gopal K. Singh and Mary Kay Kenney defend that the growing amount of data on nighttime exposure to screens enables us to grasp why sleep related problems have risen among adolescents in recent decades. The abusive usage of electronic devices prior to sleeping may result in a natural response to the reduction in sleep that is frequently experienced during this phase of development. However, this means of delaying the time of falling asleep contributes to the sleeping patterns of adolescents becoming still more irregular and shorter.

The lack of synchronicity with the biological clock, already clearly identified during adolescence, constitutes a typical pattern that continues to elicit discussion as regards the incompatibilities prevailing between biological time and social time. The usage of screens has only deepened this scenario, boosting the sleep deficit in this age group to critical levels.

Studying adolescent behaviours should take into account how these mobile devices represent an important component to their daily lives, whether for school activities or as a means of socialisation and entertainment. Irrespective of the rules that parents may establish in the house, all the recent studies demonstrate the relevance of informing young persons as regards the losses in concentration they may experience in the following morning and to correspondingly encourage them to avoid using smartphones, tablets and computers in the period prior to going to bed.


Bruni O., Sette S., Fontanesi L., Baiocco R., Laghi F., & Baumgartner E. (2015). Technology use and sleep quality in preadolescence and adolescence. Journal of Clinical Sleep Medicine, 11(12), 1433-1441.

Donskoy, I., & Loghmanee, D. (2018) Insomnia in adolescence. Medical Sciences, 6(3), 72.

Firth, J., Torous, J., Stubbs, B., Firth, J. A., Steiner, G. Z., Smith, L., Alvarez-Jimenez, M., Gleeson, J., Vancampfort, D., Armitage, C. J., & Sarris, J. (2019). The “online brain”: How the Internet may be changing our cognition. World Psychiatry, 18, 119-129.

Foerster, M., Henneke, A., Chetty-Mhlanga, S., & Röösli, M. (2019). Impact of adolescents' screen time and nocturnal mobile phone-related awakenings on sleep and general health symptoms: A prospective cohort study. International Journal of Environmental Research and Public Health, 16(3), 518.

Hale, L, Kirschen, G. W., LeBourgeois, M. K., Gradisar, M., Garrison, M. M., Montgomery-Downs, H., Kirschen, H., McHale, S. M., Chang, A., & Buxton, O. M. (2018) Youth screen media habits and sleep: Sleep-friendly screen behavior recommendations for clinicians, educators, and parents, child and adolescent. Psychiatric Clinics of North America, 27(2), 229-245.

Hysing, M., Pallesen, S., & Stormark, K. M., et al. (2015). Sleep and use of electronic devices in adolescence: Results from a large population-based study. BMJ Open, 5:e006748.

Mireku, M. O., Barker, M. M., Mutz, J., Dumontheil, I., Thomas, M., Röösli, M., Elliott, P., & Toledano, M. B. (2019). Night-time screen-based media device use and adolescents' sleep and health-related quality of life. Environment International, 124, 66–78.

Oliveira, M. L. C., Nogueira Holanda, F. W., Valdez, P., Almondes, K. M., & de Azevedo, C. V. M. (2020). Impact of electronic device usage before bedtime on sleep and attention in adolescents. Mind, Brain, and Education, 14, 376-386.

Pacheco, D., & Vyas, N. (2021, 5 de fevereiro). Screen Time and Insomnia: What It Means for Teens. Sleep Foundation.

Ponte, C., & Batista, S. (2019). EU Kids Online Portugal. Usos, competências, riscos e mediações da internet reportados por crianças e jovens (9-17 anos). EU Kids Online e NOVA FCSH.

Singh, G. K., & Kenney, M. K. (2013). Rising prevalence and neighborhood, social, and behavioral determinants of sleep problems in US children and adolescents, 2003-2012. Sleep Disorders, 394320.

Touitou, Y., Touitou, D., & Reinberg, A. (2016). Disruption of adolescents’ circadian clock: The vicious circle of media use, exposure to light at night, sleep loss and risk behaviors. Journal of Physiology-Paris, 110(4), 467-479.

Turner, P. L., & Mainster, M. A. (2008). Circadian photoreception: Ageing and the eye's important role in systemic health. The British Journal of Ophthalmology, 92(11), 1439–1444.


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