The first day of school is widely held to be more traumatic for mothers than their children, who often skip off without a backwards glance. But the fear and anxiety felt by children as the big day looms have been hugely underestimated, according to a new study.

And as thousands of parents prepare to send their children to school for the first time, researchers reported that children as young as 3 show signs of stress several months before their first term begins.

They were found to have high levels of the stress hormone cortisol up to six months before their first day at school. This rose significantly when school began and, unexpectedly, was much higher among extrovert pupils.

Scientists from the University of Bath wanted to examine how children with different temperaments coped with the stresses of starting school. They took cortisol measurements three to six months beforehand to provide a “normal” reading. However, researchers were surprised to find these readings were already high.

Fears about the forthcoming change of environment and worries about making new friends are thought to be responsible. But parents may also be to blame, for transmitting their anxiety about the day to their children.

Once school had begun, cautious and fearful pupils showed lower stress levels than exuberant children.

Julie Turner-Cobb, a senior lecturer in health psychology who led the study, which was funded by the Economic and Social Research Council, said of the findings: “This suggests that stress levels in anticipation of starting school begin to rise much earlier than we expected.

“More extrovert children had consistently higher levels of cortisol and their levels tended to remain high throughout the day, possibly because their more impulsive nature gets them into more confrontational situations.”

The degree of stress experienced by children also appeared to correlate to patterns of sickness. Consistently high levels of cortisol can suppress a person’s immune response, making them more susceptible to everyday illness. But researchers found that children with higher levels of the stress hormone when starting school were less likely to suffer from cold symptoms for the next six months and had fewer days off sick.

Dr Turner-Cobb added: “These children were more likely to get sick during the school holidays than at term time, suggesting that, at least in the short term, higher stress levels provide some protection against colds and flu.

“For most children, stress levels had lowered significantly in the six-month follow-up, suggesting that they had adapted well to the school environment. However, some children still had high cortisol levels throughout the day at follow-up, suggesting that they were experiencing a more long-term stress response.

“These children were more extroverted, but had also become increasingly socially isolated during the study, perhaps because their peers had lost patience with their exuberance.”

The study involved 105 children starting reception class. Parents completed a set of questionnaires and collected samples of their children’s saliva before, during and after their first day at school.

They also kept a diary of the child’s health and teachers completed questionnaires about the child’s behaviour and character.

Dr Turner-Cobb said the temporary stress response to starting school was natural and helped children to cope with new and potentially threatening situations through life.

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