Extra hour of screen time per day associated with poorer GCSE grades
An extra hour per day spent watching TV, using the internet or playing computer games during Year 10 is associated with poorer grades at GCSE at age 16 – the equivalent of the difference between two grades – according to research from the University of Cambridge. In a study published today in the open access International Journal of Behavioral Nutrition and Physical Activity, researchers also found that pupils doing an extra hour of daily homework and reading performed significantly better than their peers. However, the level of physical activity had no effect on academic performance.
The link between physical activity and health is well established, but its link with academic achievement is not yet well understood. Similarly, although greater levels of sedentary behaviour – for example, watching TV or reading – have been linked to poorer physical health, the connection to academic achievement is also unclear.
To look at the relationship between physical activity, sedentary behaviours and academic achievement, a team of researchers led by the Medical Research Council (MRC) Epidemiology Unit at the University of Cambridge studied 845 pupils from secondary schools in Cambridgeshire and Suffolk, measuring levels of activity and sedentary behaviour at age 14.5 years and then comparing this to their performance in their GCSEs the following year. This data was from the ROOTS study, a large longitudinal study assessing health and wellbeing during adolescence led by Professor Ian Goodyer at the Developmental Psychiatry Section, Department of Psychiatry, University of Cambridge.
The researchers measured objective levels of activity and time spent sitting, through a combination of heart rate and movement sensing. Additionally the researchers used self-reported measures to assess screen time (the time spent watching TV, using the internet and playing computer games) and time spent doing homework, and reading for pleasure.
The team found that screen time was associated with total GCSE points achieved. The average (median) amount of screen time per day was four hours: an extra hour per day of time spent in front of the TV or online at age 14.5 years was associated with 9.3 fewer GCSE points at age 16 years – the equivalent to two grades, for example from a B to a D. Two extra hours was associated with 18 fewer points at GCSE.
Screen time and time spent reading or doing homework were independently associated with academic performance, suggesting that even if participants do a lot of reading and homework, watching TV or online activity still damages their academic performance.
The researchers found no significant association between moderate to vigorous physical activity and academic performance, though this contradicts a recent study which found a beneficial effect in some academic subjects. However, both studies conclude that engaging in physical activity does not damage a pupil’s academic performance. Given the wider health and social benefits of overall physical activity, the researchers argue that it remains a public health priority both in and out of school.
As well as looking at total screen time, the researchers analysed time spent in different screen activities. Although watching TV, playing computer games or being online were all associated with poorer grades, TV viewing was found to be the most detrimental.
As this was a prospective study – in other words, the researchers followed the pupils over time to determine how different behaviours affected their academic achievement – the researchers believe they can, with some caution, infer that increased screen time led to poorer academic performance.
“Spending more time in front of a screen appears to be linked to a poorer performance at GCSE,” says first author Dr Kirsten Corder from the Centre for Diet and Activity Research (CEDAR) in the MRC Epidemiology Unit at the University of Cambridge. “We only measured this behaviour in Year 10, but this is likely to be a reliable snapshot of participants’ usual behaviour, so we can reasonably suggest that screen time may be damaging to a teenager’s grades. Further research is needed to confirm this effect conclusively, but parents who are concerned about their child’s GCSE grade might consider limiting his or her screen time.”
Unsurprisingly, the researchers found that teenagers who spent their sedentary time doing homework or reading scored better at GCSE: pupils doing an extra hour of daily homework and reading achieved on average 23.1 more GCSE points than their peers. However, pupils doing over four hours of reading or homework a day performed less well than their peers – the number of pupils in this category was relatively low (only 52 participants) and may include participants who are struggling at school, and therefore do a lot of homework but unfortunately perform badly in exams.
Dr Esther van Sluijs, also from CEDAR, adds: “We believe that programmes aimed at reducing screen time could have important benefits for teenagers’ exam grades, as well as their health. It is also encouraging that our results show that greater physical activity does not negatively affect exam results. As physical activity has many other benefits, efforts to promote physical activity throughout the day should still be a public health priority.”
The research was mainly supported by the MRC and the UK Clinical Research Collaboration.
Corder, K et al. Revising on the run or studying on the sofa: Prospective associations between physical activity, sedentary behaviour, and exam results in British adolescents. International Journal of Behavioral Nutrition and Physical Activity; 4 Sept 2015.
The paper will be freely accessible after the embargo at:
About the University of Cambridge
The mission of the University of Cambridge is to contribute to society through the pursuit of education, learning and research at the highest international levels of excellence. To date, 90 affiliates of the University have won the Nobel Prize.
Founded in 1209, the University comprises 31 autonomous Colleges, which admit undergraduates and provide small-group tuition, and 150 departments, faculties and institutions.
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About the Medical Research Council
The Medical Research Council is at the forefront of scientific discovery to improve human health. Founded in 1913 to tackle tuberculosis, the MRC now invests taxpayers’ money in some of the best medical research in the world across every area of health. Thirty-one MRC-funded researchers have won Nobel prizes in a wide range of disciplines, and MRC scientists have been behind such diverse discoveries as vitamins, the structure of DNA and the link between smoking and cancer, as well as achievements such as pioneering the use of randomised controlled trials, the invention of MRI scanning, and the development of a group of antibodies used in the making of some of the most successful drugs ever developed. Today, MRC-funded scientists tackle some of the greatest health problems facing humanity in the 21st century, from the rising tide of chronic diseases associated with ageing to the threats posed by rapidly mutating micro-organisms. www.mrc.ac.uk
About the MRC Epidemiology Unit
The MRC Epidemiology Unit is a department at the University of Cambridge. It studies the genetic, developmental and environmental factors that cause obesity, type 2 diabetes and related metabolic disorders. The outcomes from these studies are then used to develop strategies for the prevention of these diseases in the general population. www.mrc-epid.cam.ac.uk
About the Centre for Diet and Activity Research (CEDAR)
The Centre for Diet and Activity Research (CEDAR) is studying the factors that influence dietary and physical activity related behaviours, developing and evaluating public health interventions, and helping shape public health practice and policy. CEDAR is one of five Centres of Excellence in Public Health Research funded through the UK Clinical Research Collaboration. It is based in the MRC Epidemiology Unit, and is a partnership between the University of Cambridge, the University of East Anglia and MRC Units in Cambridge. The Centre acknowledges the support of the Medical Research Centre, National Institute for Health Research, Wellcome Trust, British Heart Foundation, Cancer Research UK, the Economic and Social Research Council, and the University of Cambridge. www.cedar.iph.cam.ac.uk