This post is by regular contributor Naomi Cook.
We are not ‘T.V people.’ However, my three year old enjoys an educational DVD whilst I make dinner and she also enjoys educational apps on my iPhone. I have seen tremendous learning outcomes from both of these forms of screen time. I frequently find these forms of entertainment a lifesaver, blissful relief from incessant ‘why’ questions and demands for yet another outfit change at the end of a busy day. Sometimes I feel guilty for feeling that relief… I am aware that this ‘tech-savvy toddler’ generation is a new phenomenon. I often wonder how much screen time she should have at this tender age. How much is too much? How much could be considered beneficial?
The Sydney Study 1
A recent study has shown that children who spend hours watching television every day are prone to developing narrowed arteries in the eyes. According to researchers in Sydney, this may signify an increased chance of developing cardiovascular disease in the future. 3
The study looked at over 1700 children, aged six. Some children were active and sporty, the others were more sedentary and had more screen time. The children that were more active had wider arteries in their retina than the less active children who had more screen time. 1
- You may be wondering what the size of blood vessels in the retina has to do with evaluating the risk of cardiovascular disease! However, narrowed blood vessels in the retina are commonly used as markers for high blood pressure and heart disease. 2,3,4
- According to the researchers the “magnitude” of each hour of screen time per day can be compared to a 10mmHg increase in systolic blood pressure. 1 For example; a blood pressure increase of 120/80 to 130/80. Children spent an average of 1.9 hours with screen time and an average of 36 minutes in outdoor play. 3, 4 Those who spent more than an hour playing outdoors daily had wider retinal arteries than those spending less. 4
- The authors claim that the issue is not the screen time itself that is the problem, rather the time spent being sedentary. 2 However as we know, the more the screen time, the greater the inactivity.
- One of the authors of the study has been quoted saying that over 1.5 hours of screen time a day was enough to see adverse effects on the blood vessels. 4
As a direct consequence of reading this article I became even stricter with monitoring my daughters screen time; sixty minutes is our daily limit.
Since this is the first study of its kind we can look forward to further research in this area. Hopefully future studies will look at things such as whether or not the microvascular changes are reversible over time with increased levels of activity. I also hope that future studies will continue to separate out types of sedentary activity, for example reading and puzzles versus ‘screen time’ in addition to active indoor as opposed to active outdoor play.
How do you manage your children’s screen time? How much do you think is too much?
- Gopinath B, Baur L, Wang J, Hardy L, Teber E, Kifley A, Wong T and Mitchell P (2011) Clinical and Population Studies: Influence of Physical Activity and Screen Time on the Retinal Microvasculature in Young Children Arteriosclerosis, Thrombosis and Vascular Biology 2011, 31:1233-39
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