Too Much Tv In Childhood Affects Adult Health

Too Much Tv In Childhood Affects Adult Health: Otago Study

Watching too much television as a child has long-lasting effects on adult health, according to a world-first University of Otago study about to be published in the leading international medical journal Lancet.

The study has followed a group of around 1000 children born in Dunedin in 1972-73. Every two years between the ages of 5 and 15, they were asked how much television they watched. The researchers found that those who watched the most television had the most health problems as young adults.

“We found that childhood television viewing was associated with being overweight, unfit, having high blood cholesterol and smoking cigarettes,” says Dr Bob Hancox, Deputy Director of the Dunedin Multidisciplinary Health and Development Research Unit at the Dunedin School of Medicine.

Looking further at the data, the researchers found that the health effects of television viewing could not be explained by family, socio-economic or other factors. “It’s not just that children who were already overweight decided to watch more television. Rather, children who watched a lot of television were likely to become overweight. Similarly, the association between watching television and smoking was not explained by the fact that heavy television viewers came from smoking families.”

“Our findings show that watching television is an important risk factor for poor health - we can estimate that exceeding the two hours per day limit recommended by the American Academy of Pediatrics caused 17 per cent of overweight, 15 per cent of poor fitness, 15 per cent of raised cholesterol and 17 per cent of smoking at age 26.”

Most children in this study watched more than the suggested two-hour limit. The average viewing hours were two hours and 20 minutes per weekday (not including weekends).

Other studies have already shown that heavy television viewers have a range of health problems, but this is the first study to show that the harmful effects of television persist from childhood into adulthood. Television viewing in younger children (aged 5-11) and adolescents (aged 13 & 15) had similar harmful effects.

“These findings suggest that reducing television viewing should become a health-gain priority. Parents, communities and society should work together to reduce children’s viewing hours. Adults would also benefit if they lead by example and turn off the TV,” says Dr Hancox.

The study, titled “Association between child and adolescent television viewing and adult health: a longitudinal birth cohort study” was authored by Dr Robert Hancox (DMHDRU), Mr Barry Milne (Department of Preventive and Social Medicine) and Associate Professor Richie Poulton (DMHDRU) and is published in this Saturday’s Lancet.

Notes to the Editor:

POTENTIAL EXPLANATIONS OF FINDINGS: The developed world is experiencing an epidemic of childhood and adult obesity. Excessive television viewing is one factor that all of these countries have in common. In some countries, children spend more time watching television than they do in school. Our data indicate that this is also true in New Zealand.

Television may lead to poor health through a number of ways: 1. Watching television may take up time that would have otherwise been spent in more active pursuits. In this study, adolescent television viewing was associated with reduced levels of physical activity.

2. Although television adverts for tobacco were banned in 1963, tobacco imagery has been common on children’s television (Thomson & Wilson NZ Med J 1978). Watching televised sport has been associated with smoking in New Zealand schoolchildren.

3. Television advertising in New Zealand during children’s viewing time tends to promote an unhealthy diet (Hammond et al Aust N Z J Public Health 1999, Wilson et al Aust N Z J Public Health 1999).

LIMITATIONS OF THE STUDY: Only seven per cent of children watched less than one hour of television a day. These were the healthiest, but were too few children in this group to be certain whether reducing television to less than one hour a day would be better than keeping below the two hour limit.

These children grew up in the 1970s and 1980s. During this time New Zealand had only two television channels and, unlike today, most homes had only one television set. Video recorders were only introduced towards the end of this period, computers and games consoles were rare, and the internet had not been heard of. The opportunities for “screen-time” are much higher for children today.

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