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Why does this matter?

Screen time risks are a significant concern for many parents and health professionals, and research from Australia has found it is the top child health concern for parents. Adolescents are also recognising an issue, with 90% of teens saying 'spending too much time online is a problem for teenagers' (and 60% saying it's a major problem). This section will review the risks associated with screen use and summarise current research.

Key Takeaways

High screen use has been associated with negative impacts on​:
Physical and mental health
Neurological impacts
Social / emotional impacts

Physical and mental health


Numerous studies report negative physical and mental health outcomes associated with screen time, including headaches, tendon injuries, neck and back injuries, obesitydepressionanxiety and low self-esteem.


More than 3 hours of screen time per day has been associated with computer vision syndrome in 90% of users, regardless of content, according to the US national institute of Occupational health and safety. 


Dry eye disease, where an insufficient tear film causes permanent damage to the surface of the eye, has been directly associated with screen use. Hours of daily screen use in children have been found to predict number of symptoms.

A significant increase in childhood myopia (short-sightedness) is thought to be due to a displacement of outdoor activity associated with increased screen use. 

Headphone use is associated with hearing loss in children, due to not only volume but length of exposure. The World Health Organisation has highlighted headphone use associated with devices as a significant risk to hearing for young people.


A large population-based study by Hysing et al (2015)  found that sleep disruption occurred not only from using devices in the hour before sleep, but was correlated with the total number of screen hours used during the daytime as well. 


Research into media use and adolescent mental health has shown mixed results. In a study by Twenge, Martin, Cambell & Keith (2018), media use (including social media, texting, gaming and surfing the net) of more than 5 hours a week was associated with negative impacts on the mental health of teens. Further research identified that more than one hour of recreational screen use per day in children and adolescents was associated with lower psychological well-being, lower self-control, lower emotional stability, increased distractibility and inability to finish tasks, (Twenge & Campbell, 2018). A large study by Orben & Przybylski (2019) found a weak negative association between digital technology use and adolescent well-being, and they concluded that moderate use of computers is unlikely to harm adolescent well-being. Dr Ben Carter, Senior Lecturer at Kings College in London, noted in reaction to this article that more specific definitions of 'technology use' may be helpful for future research. He also noted that studies included in this analysis dated back to 2007, which make findings hard to relate to adolescents of 2019. Further research is needed in this area.




Concerns about the impact of screen time on child and adolescent development have been raised due to the outcomes of scientific studies. Negative impacts that have been found are often from moderate or heavy use of screens, and all use is not equal. However, with almost 70% of NZ 9-year-olds now completely unsupervised and unrestricted on devices (CensusAtSchool), and with studies showing an average of 6 - 9 hours of recreational screen use per day by tweens and teens, the amount of device use in schools must be considered in the wider community context. The following results again suggest to us that while digital fluency and skills are important for children to develop, a need for balance and consideration is also essential when using digital technologies with young people.


Developmental concerns include:


Neurological development


There is increased dopamine release with reward-based gaming. MRI studies have shown a correlation between gaming and anatomical impacts on brain reward centres and structure. Anatomical changes to brain structure have been shown from relatively low amounts of gaming, as much as half an hour a day over 2 months, or even from 10 hours in one week. These studies are small and further research is needed.


Some changes have positive inferences, such as increased grey matter in brain areas involved with visual navigation and strategic planning, during games with strategy content. Other studies show reduced cortical grey matter and myelination in certain areas.


A study of 4,500 9 and 10-year-olds found that many of those who spent more than 7 hours a day on screens had premature thinning of their cerebral cortex, the area of the brain involved in higher order thinking. Whether the screen time caused the thinning or children with prematurely thinned cortexes are likely to have more screen time is unclear. The study is ongoing and future results will help to clarify cause and effect.


Reward-based gaming has been linked to structural brain changes in the reward circuitry that resemble the effects of substance addiction. Long-term outcomes on behaviour are unknown. However again, researchers hypothesise that 'excessive usage could be changing children’s brain reward systems in the long term, making them more susceptible to other addictions later in life.' Studies do seem to support this association.


Social media addiction has also been linked to the same structural changes to brain appearance as substance addictions.


Children are thought to be at higher risk due to the increased plasticity of their brains. See 'Reward-based gaming' for further information.


This research is in the early stages and there are study limitations, but there appear to be risks, and these risks may impact on different populations differently. Some health professionals are concerned and further research is underway. 


At this stage, we have to consider the questions - do the potential gains from reward-based gamification of learning outweigh the risks? Should parents be able to opt out? Can populations be targeted that may benefit, without disadvantaging other groups? Do there need to be guidelines on the amount of reward-based educational gaming schools prescribe both during and out of school hours, and do these need to take into consideration the amount of recreational gaming children do out of school hours?


Further impacts: Memory, attention and cognition

In a randomised controlled trial, heavy smartphone use increased users' impulsivity and decreased their ability to process information, (1). 'Habituating oneself to constant immediate gratification could have significant and lasting cognitive consequences.'


While further research is needed, the evidence that does exist suggests that heavy smartphone use is associated with reduced memory functioning, including visual, working, spatial memory. 'The available evidence suggests that when we turn to these devices, we generally learn and remember less from our experiences,' (Wilmer et al, 2017).


Studies have found an increased risk of behavioural problems including inattention, and lower cognitive skills in young children with higher screen use. This includes research by Tamana et al (2019) which found that children exposed to 2 hours of screen use per day were 7 times more likely to meet the criteria for ADHD than children with 1/2 an hour of screen use per day, at age 3 and 5 years. “The two big takeaways from this study are that children exposed to more screen time, at either age 3 or 5 years, showed significantly greater behavioural and attention problems at age 5, and that this association was greater than any other risk factor we assessed, including sleep, parenting stress, and socioeconomic factors,”noted author Sukhpreet Tamana, a postdoctoral fellow in the Department of Pediatrics at the University of Alberta.


Research has shown similar effects on attention at 4.5 years of age in young children exceeding one hour of screen use per day.


While these studies show negative associations with screen use and attention for younger children, a recent study found that symptoms of ADHD developed in teens with a higher frequency of digital media use, when they previously did not have symptoms.


Social / emotional impacts


Social skills

Higher frequency of screen time has been associated with reduced ability to empathise, and more difficulty making friends.


“Many people are looking at the benefits of digital media in education, and not many are looking at the costs,” said Patricia Greenfield , a distinguished Professor of Psychology in the UCLA College and senior author of the study. “Decreased sensitivity to emotional cues - losing the ability to understand the emotions of other people - is one of the costs. The displacement of in-person social interaction by screen interaction seems to be reducing social skills.”


Nicholas Tampio, Associate Professor at Fordham University, echoes this view in an interview with Radio New Zealand. "Significant screen use is eroding empathy," he says; "this occurs regardless of content, not only because of violent gaming." 


Understanding non-verbal communication is crucial, and is associated with personal, academic and social success. Non-verbal cues are much stronger when communicating face to face rather than digitally. Extensive use of digital communication can impact negatively on the development and mastery of social skills.


Special populations

Children with ADHD and Autistic Spectrum Disorder (ASD) have been found to be at higher risk of experiencing negative effects from screen time, and of developing internet and video gaming addictions, (2,3,4,5).


Cyberbullying within school hours

Cyberbullying and the increased risk of self-harm/suicide by victims are significant reasons why smartphone use in schools is being reassessed in other regions. New Zealand youth have recently been found to have among the highest cyberbullying rates in the world. Several websites and organisations can offer support if you have these concerns for your child, such as bullyingfreenz, or resource lists from the NZ police website.


Inappropriate content access

Even children at primary school level are accessing inappropriate and R-rated content during school hours as reported by both teachers and parents. This is occurring despite protective services, not just with VPN's.


recent poll held in New Zealand found that 36% of families reported that they knew their child had been exposed to inappropriate R-rated content when using the internet within school hours. This was described as sexual content, extreme hate sites, violent/R18 gaming, or similarly-rated content. Exposure had occurred in all school levels (primary to secondary), and a frequent comment was that the teacher or parent's knowledge of the incident was only discovered by chance. This suggests that the true extent of this problem is likely to be far higher than the result this type of poll can capture. Further research is needed in this area.


In New Zealand, children as young as 8 years old have seen inappropriate sexual content on school devices. While some schools may minimise this issue, the impact of viewing pornography for children can have both immediate and cumulative problems.


Pornography exposure is thought to be shaping young people sexual attitudes and behaviours and redefining sexual norms. A New Zealand survey of 622 health providers, youth services, schools, therapists and whanau indicated an increase in youth presenting with genital injuries caused by young people reenacting violent and aggressive pornographic scenes on each other. Most survey stakeholders indicated that porn has become a primary sex educator for young people, and were concerned about the messaging that often normalises sexual violence, poor understanding of consent, sexism and misogyny towards women and girls. Principals, teachers and counsellors raised concerns, giving 'many accounts of students viewing porn on personal or devices during school hours.'


If you would like further information or support about early pornography exposure, The Light Project has excellent online resources.


Low socioeconomic groups and the 'digital divide'

There's a new concern being highlighted in studies, that our more disadvantaged communities are further affected by the downside of too much screen time - the very communities for whom technology was supposed to ‘level the playing field’ of education. There was panic about the digital divide, but some studies are finding a reversal in the pattern, with lower socioeconomic groups having significantly more screen time than their more affluent peers. Increasingly, families who can pay privately are electing lower tech schools, coining a ‘new digital divide’.


The 2015 OECD report on the use of digital technologies in school, 'Students, computers and learning,

noted that by 2012, computers were present in almost every household in the study, and often in large numbers. Almost all homes surveyed had a computer, and many had more than three. According to the Australian Child Health Poll (2017), the majority (94%) of teens own their own mobile screen-based device, 67% of primary students, 36% of preschoolers, and 17% of infants or toddlers.


"One of the most disappointing findings of the OECD report is that the socioeconomic divide between students is not narrowed by technology, perhaps even amplified," said Mr Andreas Schleicher, the OECD's education director. 


There is theoretical potential for computers to reduce the gap between students with low socioeconomic backgrounds. Margarita & Federico (2017) concluded from a meta-analysis on digital technology and learning outcomes of students from low socioeconomic backgrounds that there was a positive association between disadvantaged students achievement and the use of computers for some purposes, but only in those students with limited computer use. For medium to high users, the association was slightly negative. They also found the association was actually no different to their higher socioeconomic peers.  The researchers concluded that there was potential to improve achievement, but only to a certain degree, and that it is crucial to use computers properly in order to reap benefits.


Two studies looked at the effect of providing home computers to disadvantaged communities, and found no effect or a reduction in educational outcomes. In one group, teachers reported recipients from the free-device group exerted less effort at school compared to the non-device group. The other group noted the additional time spent on computers by the students was not spent doing homework or using educational software: they were more likely to be using the device for games on a daily basis. Problem-solving these barriers and proving supervision and support could help to get the best use of technology for disadvantaged communities. 


Family conflict

Many families are experiencing conflict, tension, and disagreement in relation to screen-based device use, with 62% reporting this finding in a recent Australian child health poll.


Data harvesting

There are issues concerning children's privacy and data harvesting, and the legal obligations for schools to consider. Data harvesting refers to the collection of information from every interaction a child has with an electronic device, such as grades, habits, disciplinary matters, attitudes, sociability and even location. A US education department has been sued for weakening privacy laws and allowing the collection of student data by private companies. Concerns have not only been expressed for students privacy, but for their intellectual freedom, when every online thought and attitude is collected and analysed.



While more research is needed, these studies suggest a level of risk, and indicate a need for balance and age-dependent guidelines for screen use in schools. Guidelines have been developed by the Baltimore Digital Health Group (comprised of paediatricians and other health professionals), who advise their School Health Council in the US. They recommend minimal screen use in education settings before starting school, and a maximum of half the learning school day on screens in high school (up to 2 1/2 hours), with a gradual increase in computer use from age 5. 


Educational impacts


Educational outcomes

Studies have mixed results with regard to the use of digital devices and the impact on educational outcomes. The results show improvements in some areas of learning but not others, and a limit to the amount of device use that can achieve those improvements.


See 'How much device use achieves the best outcomes' for more information. 



While digital devices have great potential for learning, they are frequently described as a double-edged sword due to their ease and appeal as an endless source of distraction.


Studies have shown students spend significant portions of class time being distracted by their digital devices.


The distraction occurs not only with the immediate interruption, but by 'resumption errors' - errors in performance that occur for a period of time after an interruption.


Device use has been shown not only to distract the user and reduce their comprehension and test performance, but also to distract and disadvantage those seated around them within visual range of their screen. 'Those around see the screen and attention is pulled...not just to note-taking but Facebook, Twitter, email and news,' (Dynarski, 2017).



Multi-tasking, defined as the simultaneous use of more than one form of media, has been found to increase the time it takes to complete a task, to increase errors, and to reduce attention, despite student perception often being the opposite, (6,7,8,9,10).


Research by Common Sense Media looking at 2600 children age 8 - 18 years, found that half of teens are on social media while doing homework, 60% are texting, 76% are listening to music and more than half are watching TV, (11).



Research has indicated that the physical process of forming letters when writing (which doesn’t become fluent until around age 10) is an important part of encoding letters and sounds, which impacts on the development of letter recognition and literacy. 'Keyboards cannot replicate the inherent cognitive and educational benefits that handwriting provides,'(Mann et al, 2015).


To assume the keyboard or dictation and editing is the way of the future, and to drop writing in the early stages of education may have wider reaching implications. This is quite interesting when taken in the context of declining literacy in NZ


Studies have found that students have less understanding and retention of information when taking notes in class on a laptop compared to handwriting.


A large randomised trial by Carter et al (2016) found students who had laptops and devices removed from class performed significantly better in exams than those with both restricted and unrestricted access.


The stylus has been seen by some schools as a solution that allows young students to learn to write in a digital learning environment. A stylus can allow additional functions that handwriting cannot, and can augment learning for students with special needs. However, the stylus is 'yet to be perfected' and has not been broadly adopted.


Studies have looked into the differences between pen and paper writing versus pen-based interaction with devices. They note that writing with a stylus on glass does not provide the same experience as pen and paper. The smooth glass offers limited feedback, so users have to keep an 'eyes on the screen' approach to compensate for this. Users hold their hand differently on the screen compared to paper, which can lead to fatigue. Despite technology aimed at correcting the issue, 'unintended touch,' where the device detects additional touch points from the users can be a problem, as can latency (delay in mark making). Latency does not exist with pen and paper as the ink rolls out instantly. The inaccuracy of the stylus is a common frustration, with ink not being deposited where expected. Study participants have also reported using a stylus affected writing speed and size, and they made larger, straighter and seemingly more haphazard gestures when sketching. Users report higher frustration using a stylus compared to pen and paper, and note a preference for pen and paper interface.



Digital tools have been described as 'least helpful to students learning to read.' A New Zealand MOE study found that students who engage in digital tasks 'weekly or more' have lower enjoyment of reading. The more devices children have access to with e-reading capabilities, the lower their reading frequency. While 93% of Year 5 students use computers when learning to read in NZ (compared to an international average of 44%), this year group ranked last across English-speaking countries for reading.

Print and digital texts foster different styles of reading and different ways of thinking and doing research, (Durrant & Horvana, 2015).


Studies have found students have less understanding and comprehension when reading long or complex text on devices when compared to paper as well as lower recall of information.


This is thought to be due to several processes. Scrolling is known to hamper the process of reading, by affecting the reader's spatial awareness of the text. 'A good spatial representation of the physical layout of a text supports good reading comprehension,' (Mangen et al, 2013). They note that computer readers are restricted to seeing and sensing only one page of the text at any given time. Therefore their overview of the overview of the organisation, structure, and flow of the text may be hampered.


Skim reading when online is also a common behaviour, including keyword spotting, browsing and scanning, and non-linear reading. Print reading takes longer, and students are more likely to reread.


Multi-tasking and distraction when reading online can affect concentration.


The development of empathy in reading has been found to be lower in digital format compared to print.


Research has shown a correlation indicating people who frequently use electronic devices may have more trouble comprehending scientific text. The author questioned whether the way people read on e-devices encourages them only to pick up 'bits and pieces' of information, while the comprehension of scientific information requires a more holistic approach to reading where the reader incorporates the information in a relational and structured way. 


For information on how to use this knowledge of reading differences to teach improved deep reading and digital reading skills, go to 'What's going well in education.'




References not included in hyperlinks:


1) Hadar A. A., Eliraz D., Lazarovits A., Alyagon U., Zangen A. (2015). Using longitudinal exposure to causally link smartphone usage to changes in behavior, cognition and right prefrontal neural activity. Brain Stimul. 8 318 10.1016/j.brs.2015.01.032 [Cross Ref] .


2) Dunckley, V. (2016). Autism and Screen Time: Special Brains, Special Risks. Psychology today, Dec 31.


3) Mazurek, M., & Englehart, C. (2015). Video Game Use in Boys With Autism Spectrum Disorder, ADHD, or Typical Development. Pediatrics, 132 (2): 260-266.


4) Weinstein, A,. & Weizman, A. (2012). Emerging Association Between Addictive Gaming and Attention-Deficit/Hyperactivity Disorder. Current Psychiatry Reports, 14 (5) 590-597.


5) Weinstein, A., Yaacov, Y., Manning, M., & Weizman, A. (2015). Internet addiction and attention deficit hyperactivity disorder among schoolchildren. Israel Medical Association Journal. 17 (12): 731-734.


6) American Psychological Association, (March 20th, 2006). Multitasking: Switching costs.


7) Moisala, M., Salmela, V., Salo, E., Carlson, S., Salonen, O., Lanka, K., Palmela-Aro, K., & Alho, K. (2016). Media multitasking is associated with distractibility and increased prefrontal activity in adolescents and young adults. Neuroimage, 1 (134): 113-121.


8) Ophir, E., Nass., & Wagner, A. (2009). Cognitive control in multitaskers. Proc Natl Acad Sci U S A,106 (37): 15583–15587.


9) Wood, E., Zivcakova, P., Gentile, P., Archer, K., De Pasquale, D., & Nosko, A. (2011).Examining the impact of off-task multi-tasking with technology on real-time classroom learning. Computers & Education, 58 (1): 365-374.


10) Weinschenk, S. (2012).The True Cost Of Multi-Tasking. Psychology Today.


11) Clement & Miles, (2018). Screen schooled: Two veteran teachers expose how technology overuse is making our kids dumber. Chicago, Illinois: Chicago Review Press Incorporated.

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