Infinite Scroll: How Screens Steal Sleep and Trigger Depression in Teens

Teenagers are using screens (such as cell phones and computers) much more than recommended, which can disrupt sleep and increase the risk of depression. Sleep and depression are linked: poor sleep can cause sadness and mood problems. Many countries recommend that teenagers use screens for less than 2 to 3 hours a day, but most exceed this limit. Excessive screen use can delay sleep, worsen quality of life and affect mental health, especially in girls.

During adolescence, problems related to sleep and depression are considered serious public health issues in several countries. One of the factors that has been drawing attention in this scenario is the excessive use of technologies with digital screens, such as cell phones, tablets and computers.

Research shows that both sleep difficulties and symptoms of depression appear to be linked to the time that teenagers spend in front of screens. However, previous studies have failed to clearly define whether there is a cause-and-effect relationship between these factors, which has prompted new research to better understand how screen time, sleep, and depression influence each other, also considering differences between boys and girls.

It is important to know that sleep problems are not only signs of depression, but can also be one of its causes. When we talk about depression, it is common to observe physical symptoms, such as fatigue, insomnia, and lack of appetite, along with emotional symptoms, such as low self-esteem and intense sadness.

Assessing these aspects is essential in clinical instruments, such as the Beck Depression Inventory-II, which was used in this study.

In the public health field, international recommendations have emerged to limit screen time for children and adolescents. For example, the Canadian Guidelines suggest that daily use of digital media should not exceed two hours. The World Health Organization (WHO) also recommends a similar limit for young people between the ages of 5 and 17. Countries such as Canada and Australia have officially adopted this limit of less than two hours per day.

However, studies show that most adolescents do not meet this target, especially in countries such as Australia, where around 80% of 16-year-olds exceed this amount of time. In light of this, even stricter initiatives have emerged, such as the proposal for a law in Australia that would prohibit children under 16 from having social media accounts.

Other countries, such as France, the United Kingdom and India, are also discussing similar policies. Still, it is important to know that these recommendations for limiting screen time are based on studies with evidence of low quality.

Even so, the current consensus is that the less screen time, the better for young people's health. Excessive screen time has even been linked to problems such as poorer sleep quality and increased symptoms of depression.

Some Scandinavian countries have taken practical measures, such as Norway, which banned the use of cell phones in elementary school classrooms. Other countries, such as Denmark and Sweden, have monitored screen time, but without implementing such severe restrictions.

This particular study analyzed 4,810 Swedish adolescents aged 12 to 16, living in Stockholm. It was observed that, on average, they exceeded the recommended screen time of less than 3 hours per day by one hour. Most reported spending 3 to 4 hours per day using screens for leisure, a number measured before the Swedish recommendations were published.

It is worth noting that the aim of the study was not to assess whether these public health recommendations are good or realistic, but rather to investigate how excessive screen use impacts sleep and the risk of depression in this age group, bearing in mind that most adolescents do not follow the current recommendations.

During adolescence, it is natural for sleep patterns to change: young people tend to go to bed and wake up later. This behavior is known as a late chronotype and is common up until the age of 20. This biological adjustment in sleep can be intensified by social activities, both in person and online.

However, strict school schedules remain the same, which can generate so-called “social jetlag,” a type of mismatch between weekend sleep and what is needed during the week. On days off, when they don’t have to wake up early, adolescents also tend to use screens more.

Determining whether screen use causes sleep or mental health problems, or whether these problems arise for other related reasons, is a challenge for research.

Still, prolonged screen time can increase symptoms of depression directly, indirectly, or both. Many previous studies have not been designed to prove cause and effect, and this study did not definitively investigate causality, although it did look at the time sequence of events.

Several studies indicate that screen time can negatively affect mental health because it reduces the time spent on healthy behaviors, such as sleep. This phenomenon is called the “screen-sleep shift,” and it may or may not lead to depression.

The idea that screen time disrupts sleep has been around since at least the 1980s, when limits on television time were discussed. Sleep shifts can occur in a number of ways: for example, if teens trade off hours of sleep to spend more time on their phones, if the content they consume is too exciting or stressful, or if the light emitted by screens interferes with the production of melatonin, the hormone that regulates sleep.

In these cases, screen time does not directly harm mood, but it does so indirectly, first by affecting sleep. Studies show that the negative impact of screen time on depression often occurs because sleep worsens.

In addition, factors such as gender appear to influence these relationships: girls are more likely to experience negative effects related to screen time and depression. For boys, excessive screen time may be more associated with symptoms of inattention, impulsivity and behavioral disorders, such as ADHD.

Excessive screen time can also be detrimental to other aspects of a healthy lifestyle, such as exercise, proper nutrition, and the quality of social relationships, which makes the relationship between screen time, sleep, and mental health even more complex.

This study did not attempt to correct for all these possible external influences, but it did select a large, random, and representative sample of the young population of Stockholm, which gives some confidence that the results reflect reality.

Even so, there are limitations, such as the fact that adolescents who missed school were not included in the study. In September 2024, Sweden published its first official public health guidelines on digital media use by adolescents. These recommendations set limits on screen time for leisure (i.e., activities that do not involve school), excluding time spent listening to music or podcasts.

Sweden, like other countries, suggests that parents monitor screen time, especially for younger children. One of the main concerns is improving the quality of sleep in adolescents, which is why it is recommended to avoid screen time close to bedtime. The limits indicated are less than 3 hours per day for teenagers aged 13 to 18, and less than 2 hours for children aged 6 to 12.

READ MORE:

Adolescents’ screen time displaces multiple sleep pathways and elevates depressive symptoms over twelve months

Sebastian Hökby, Jesper Alvarsson, Joakim Westerlund, Vladimir Carli and Gergö Hadlaczky,

PLOS Global Public Health. 2 April 2025

DOI: 10.1371/journal.pgph.0004262

Abstract:

Recently the Swedish Public Health Agency published recommendations of a maximum of two-to-three hours of daily leisure screen time for adolescents aged 13–18, partly to promote better sleep (2024-Sep-02). Biologically and socially, adolescence is characterized by belated sleep times, and depressive effects of screen time can arise through sleep displacements. Theorized links between screen time, sleep, and depression, merited examination of four sleep mediators to determine their relative importance and determine which of them mediate future depression. Hypotheses were preregistered. Three-wave psychometric health data were collected from healthy Swedish students (N = 4810; 51% Boys; ages 12–16; N = 55 schools; n = 20 of 26 Stockholm municipalities). Multiple imputation bias-corrected missing data. Gender-wise Structural Equation Modelling tested four sleep facets as competing mediators (quality, duration, chronotype, social jetlag). The primary model result included the three first mediators to achieve acceptable fit indices (RMSEA = 0.02; SRMR = 0.03; CFI = 0.95; TLI = 0.94). Screen time deteriorated sleep within three months and effect sizes varied between mediators (Beta weights ranged: 0.14–0.30) but less between genders. Among boys, screen time at baseline had a direct adverse effect on depression after twelve months (Beta = 0.02; p <0.038). Among girls, the depressive effect was mediated through sleep quality, duration, and chronotype (57, 38, 45% mediation). Social jetlag remained non-significant. This study supports a modernized ‘screen-sleep-displacement theory’. It empirically demonstrates that screen-sleep displacements impact several aspects of sleep simultaneously. Displacements led to elevated depressive symptoms among girls but not boys. Boys may be more prone to externalizing symptoms due to sleep loss. Results could mirror potentially beneficial public health effects of national screen time recommendations.