Five-year-olds who watch three or more hours of television per day may be at an increased risk of developing antisocial behaviours, such as fighting, by the age of seven, a new study indicates.

However, the risk is small and playing computer games appears to have no impact on behaviour at this age.

According to researchers from Glasgow, while too much screen time has been linked to different behavioural and emotional problems in children, most of the relevant studies have looked only at television and almost all have been carried out in the US.

They carried out a study involving over 11,000 children aged five to seven, with the aim of assessing the psychological and social impact of watching television and playing computer games.

The children's mothers were asked how well adjusted their children were when they were five years old and again when they were seven. Issues such as conduct problems (antisocial behaviour), poor attention span, emotional problems and difficulty making friends were all considered.

The mothers were also asked how much time the children spent watching television and playing computer games at the age of five.

At this age, almost two-thirds of the children watched between one and three hours of TV per day, while around one in seven watched more than three hours per day. A tiny minority - less than 2% - watched no television.

However, at this age, the children did not spend a lot of time playing computer games. Just 3% spent three hours or more playing them every day.

The researchers from the University of Glasgow found that when other factors were taken into account, such as family dynamics, children who watched more than three hours per day of television had a small increased risk of developing conduct problems, such as fighting and stealing, by the age of seven.

However watching a lot of television did not appear to increase the risk of emotional or attention problems.

Playing computer games did not appear to affect behaviour either, however the researchers noted that this may simply be because the children were not playing a lot of these games anyway.

They suggested that the links to behavioural and emotional problems may be indirect. For example, watching a lot of television can lead to sedentary behaviour and poor sleeping habits.

However, they said that the findings ‘suggest that a cautionary approach to the heavy use of screen entertainment in young children is justifiable in terms of potential effects on wellbeing, particularly conduct problems, in addition to effects on physical health and academic progress shown elsewhere'.

Details of these findings are published in the journal, Archives of Disease in Childhood.