By Dr Aric Sigman
We must prevent children under three from watching television or risk irreversibly damaging their health.
It may sound shocking but, rest assured, far from being a Luddite, I am enjoying my brand-new iMac and we own a television set.
Over the past ten years I have been collating data and my discoveries have troubled me greatly – both as a biologist and as a parent.
Last month, I presented my findings to MEPs in Brussels. My message was unequivocal.
In many ways Teletubbies, or any other educational programme for children, could be as physiologically damaging as a violent video game.
So, how does watching something on a screen – whether TV, a DVD, computer games or surfing the internet – have a negative impact, more so than other sedentary activities such as reading or knitting?
It is because we are instinctively transfixed by television. It elicits the orienting response – our sensitivity to movement and sudden changes in vision or sound.
These images on screen trigger what psychologists call attentional inertia – we are dazzled and cannot take our eyes off the screen.
Screen time also triggers the release of dopamine, a brain chemical that is involved in learning and concentration. When we see or experience something new, dopamine is released in the brain. Its effect is to focus our attention.
The surges caused by regular screen time may mean the brain becomes desensitised, so when the child later has to concentrate on something that does not have the same hyper-stimulating effect – a book or a teacher – they find they cannot do so. It’s a bit like the way that those who add salt to their food find unsalted food tastes dull.
About 80 per cent of brain development happens before we are three, and screen time at this age seems to be particularly damaging.
Scientists have observed effects ranging from the immediate release of hormones into the blood, which can contribute to long-term health problems, to actual physical changes in the brain and learning disorders.
A study from the University of Florence in 2006 of children aged six to 13 who spent an average amount of time watching TV found that their levels of melatonin – a hormone that causes us to sleep, but is also important for a healthy immune system and regulating the onset of puberty – shot up by 30 per cent after one week with no screen time.
Hormones related to metabolism are also affected. A study at the University of Sydney published this summer found that of a group of 290 boys aged 15, those who watched TV or DVDs or played computer games for more than two hours a day had elevated levels of chemical markers related to the development of coronary heart disease in later life.
These findings were backed up by a study from Birmingham University that found women who watched TV during a meal were likely to snack more in the hours after. One theory is that screen time interrupts the release of chemicals in the blood linked to hunger and satiation. Or perhaps memory is affected, so we forget we have eaten.
At the other end of the spectrum, a study this year from the Heart and Diabetes Institute, Melbourne, found that each daily hour of TV viewing in adulthood was associated with an 18 per cent increase in death from heart disease. Those who watched four or more hours were 80 per cent more likely to suffer a fatal heart condition.
By the age of 75 the average Briton will have spent more than 12 years watching television. Those aged 11 to 15 now spend 50 per cent of their waking lives – 42 hours a week, six hours a day – in front of a screen.
The good news? If you turn the TV off these ill-effects can be prevented or reversed. After all, there are no health risks to reading a good book.