Screen time is the amount of hours spent using an electronic device with a display screen emitting blue light, such as a smartphone, computer, television, video game console, or tablet. The concept is under significant research with related concepts in digital media use and mental health. Screen time is correlated with mental and physical harm in child development. The positive or negative health effects of screen time on a particular individual are influenced by levels and content of exposure. Screen time is known to increase dopamine and mess with the circadian rhythm. To prevent harmful excesses of screen time, some governments have placed regulations on usage.
History An early researcher who worked on the first electronic computer at Princeton in the 1950s alongside John von Neumann, "insisted on using punched cards, even when everybody had computer screens." Amongst the reasons that he gave for this, we find the statement that, "when you sit in front of a screen your ability to think clearly declines because you're distracted by irrelevancies." This early intuition has since been verified by dozens of studies.
Statistics The first electronic screen was the cathode ray tube (CRT), which was invented in 1922. CRTs were the most popular choice for display screens until the rise of liquid crystal displays (LCDs) in the early 2000s. Screens are now an essential part of entertainment, advertising, and information technologies.
Since their popularization in 2007, smartphones have become ubiquitous in daily life. In 2023, 85% of American adults reported owning a smartphone. An American survey in 2016 found a median of 3.7 minutes per hour screen use per citizen. All forms of screens are frequently used by children and teens. Nationally representative data of children and teens in the United States show that the daily average of screen time increases with age. TV and video games were once largest contributors to children's screen time, but the past decade has seen a shift towards smart phones and tablets. Specifically, a 2011 nationally representative survey of American parents of children from birth to age 8 suggests that TV accounted for 51% of children's total daily screen time, while mobile devices only accounted for 4%. However, in 2017, TV dropped down to 42% of children's total daily screen time, and mobile media devices jumped up to 35%.
+Average daily screen time of American children & teensAge group (in years)Daily average screen timeYear data was collectedUnder 242 minutes20172–42 hours20175–82 hours20178-106 hours202411-149 hours2024
Race, socioeconomic class, and screen time Research has shown that race and socioeconomic class are associated with overall screen time. Younger demographics and individuals who self-identified as Black and "Other" were associated with above-average screen use. Additionally, Black and Latino Americans had longer screen times because of less access to desktop computers, which thus leads to more time on phones. In children, the divide is much larger. On average in 2011, White children spent 8.5 hours a day with digital media, and Black and Latino children spent about 13 hours a day on screens. Black and Latino children were also more likely to have TVs in their rooms, which contributed to their increased use of screen time.
The discrepancy in the amount of screen time can also be attributed to a difference in income. In more affluent private schools, there has been a larger push to remove screens from education in order to limit the negative impacts that have been found from screen time. However, in public schools there is more push for the use of technology with some public schools advertising free iPads and laptops to students. Additionally, affluent families can afford nannies and extracurriculars that can limit the need for entertainment from screens.
Effects of COVID-19 pandemic The COVID-19 pandemic in 2020 increased screen time as people stayed indoors, adding to concerns about the effects of excessive screen time. Specialists called for limiting screen time and for living a more active lifestyle.
Studies have shown that even after children returned to school following a period of online schooling, which significantly increased daily screen time, their level of physical activity has remained low, while screen time has increased. Due to the increase in screen time, many children gained weight during this time.
Physical health effects Sleep More screen time has been linked with shorter sleep duration, decreased sleep efficiency, and longer sleep onset delay. When using any screen before bedtime, the blue light emitted disrupts the body's natural melatonin hormone production. Melatonin is produced by the brain's pineal gland and controls the body's internal clock. This clock is what is referred to as the body's circadian rhythm and it naturally is responsive to light. Melatonin levels increase as the sun sets and remain at that increased state for the remainder of the night. As the sun rises, melatonin levels start to drop. This hormone reduction is what helps the body's natural rhythm wake up due to the bursts of natural sunlight. The light screens emit is in a similar spectrum of sunlight, but the blue light emission is what human circadian rhythms are most sensitive to. Studies have shown that the blue wavelengths are closely correlated to those from sunlight, which is what helps the body keep in sync with the sunrise and sunset. Therefore, using any screen prior to bedtime disrupts the body's production of natural bedtime hormones which can trick the brain to believe it is still daytime making it harder to fall asleep.
Increased use of screens in children has also been shown to have an association with adverse effects on the quality of sleep in children. A 2010 review concluded that "the use of electronic media by children and adolescents does have a negative impact on their sleep, although the precise effects and mechanisms remain unclear", with the most consistent results associating excessive media use with shorter sleep duration and delayed bed times. A 2016 meta-analysis found that "Bedtime access and use of media devices was significantly associated with inadequate sleep quantity; poor sleep quality; and excessive daytime sleepiness". This relationship is because much of the time spent on screens for children is at night, which can cause them to go to sleep later in addition to the blue light from the screens making it more difficult to sleep. However, the relationship between screen use and sleep may not be the same across neurotypical and neurodivergent children. There are reasons to believe that autistic children, for example, may be more interested in screens than their neurotypical peers, and less able to disengage from them. A 2025 systematic review found that a causal link between screen-time use and sleep in autistic children could not be established based on available research findings at the time.
Night-time use of screens is common for Americans ages 12–18: A 2018 nationally representative survey found that 70% use their mobile device within 30 minutes of going to sleep. Data suggests those who had spent more time on their screens were more likely to wake in the night from notifications on their phone, or experience disruptive sleep. In a series of nationally representative surveys, 36% of Americans age 12–18 and 35% of Mexican teens age 13–18 woke up during the night before to check their mobile device. For American children and teens, 54% of those did so because of getting a notification and 51% did so because of the desire to check social media. Content that stirs emotions has been linked with a delay in the onset of sleep.
Many apps promise to improve sleep by filtering out blue light produced by media devices; there have been no large studies to assess whether such apps work. Some users express dissatisfaction with the resultant orange tint of screens. Some people use blue-blocking glasses for the purpose of attempting to block out blue light both from electronic media and from other artificial light sources. The American Academy of Pediatrics recommends that the screen time of children be limited for multiple reasons, including that "Too much screen time can also harm the amount and quality of sleep".
Effects on physical health As well as negatively impacting the adult sleep cycle, using screens can also affect one's physical health. Obesity is commonly correlated with big screen times. Studies have suggested that if the amount of screen time adolescents spend was limited, the likelihood of obesity can be reduced. However, the associations between discretionary screen time and adverse health outcomes were strongest in those with low grip strength, fitness and physical activity and markedly attenuated in those with the highest levels of grip strength, fitness and physical activity.
This sedentary behavior is largely due to the nature of most electronic activities. Sitting to watch television, playing computer games or surfing the Internet takes time away from physical activities which leads to an increased risk of weight gain. It has been found that children (kindergarten and 1st graders) who watch 1–2 hours of television a day are more likely to be overweight or obese than children who watch less than one hour a day. Additionally, one study showed that the increased use of video games and other forms of media consumption led to more back pain among Norwegian teens.
It has been reported that screen time negatively affects health in children independently of their physical activity and eating habits. One possible explanation for the link between TV and obesity is the number of commercials for sugary and unhealthy foods. This advertising can affect what gets purchased and consumed in a household. The effect of advertising was demonstrated in a study where children were shown cartoons with and without food commercials. The children who watched the food commercials along with the cartoons ate 45% more unhealthy snacks than the group who watched the cartoons without food ads.
Mental health effects
As previously discussed, sleep and screen time are heavily impacted by the other and can lead to affecting one's behavior as well. If someone does not get an adequate amount of sleep, it can affect their behavior and performance for the day. High amounts of screen time also can significantly affect a person's mental health, although some have called these findings into question. Excessive screen usage is linked with many mental health effects in children. A systematic review by Santos et al. pointed out that social media use was linked with depressive symptoms among mostly girls and that recreational screen time was linked to negative psychological effects on these children and teens. With screen usage increasing as time progresses, adults have begun spending more and more time focusing their attention on screens and not their own kids. This time spent sitting and viewing a screen has been linked to mental health effects such as anxiety and depression. Adults with screen times of six hours or greater are more likely to suffer from moderate to severe depression. This increased screen time has been shown to be directly correlated with an increased chance of depression in adults. With this added risk, lack of sleep plays a major role in a healthy mindset, and without proper rest, mental health can degrade at a higher rate.
Brain development