Row over daycare stress claims

In Mother superior? The biological effects of daycare, Dr Sigman, (right), says that studies have found that children show increasing levels of the stress hormone cortisol when they spend time in childcare.

Research shows that there is a link between high cortisol levels and heart disease, he says.

The article, which is published in The Biologist journal, cites studies that show that cortisol levels increase in children in daycare up until the age of three.

Writing on his website Mr Sigman acknowledges that the issue is controversial, and says that he deliberately chose negative studies because most biologists and policy makers do not know about them.

‘The intent is to redress an existing imbalance in the perception of daycare as a "complex, waiting to be understood- but at the moment benign" lifestyle practice.’

Dr Sigman says that, ‘Few stop to consider that daycare is an evolutionary novelty, which has grown suddenly and rapidly.’

He adds, ‘The accepted position at the moment considers daycare attendance as an accepted healthy practice, which both scientists and society must consider equivalent in terms of child wellbeing and later development.’

While he says that ‘the longterm effects of daycare and cortisol release are not fully understood’, he adds that it is ‘justified and prudent’ to emphasise the possible negative implications.

However, Dr Sigman has been criticised by other experts who dispute his claims.

'Mild stress can be good'

Dorothy Bishop, professor of developmental neuropsychology at Oxford University, said that while there is evidence that cortisol levels rise in young children attending nursery, this does not mean that children’s health is at risk.

Professor Bishop said, ‘There is good evidence that cortisol levels rise in children who attend daycare throughout the day, whereas they don’t in those who stay at home. This has been shown both in comparisons of children who do and don’t attend daycare, and in the same children, depending on whether or not they are at nursery or home. Cortisol is an indicator of stress.

'The real issue is whether this is detrimental to children’s development. Sigman emphasises all kinds of negative consequences of elevated cortisol levels, but most of this comes from people who have long-term chronic elevation of cortisol; this is very different from what is seen in children. The studies on health risks mainly come from the over 65’s.’

She added, ‘Meanwhile, many scientists who work on stress note that it’s not an absolute good or bad - mild levels of stress can be good for development. There are some studies that suggest you can get increased resilience from mild stress, provided it doesn't go on for a long time.’

‘So you could argue that nursery can be beneficial to children in teaching them to cope with novelty and separation from parents. It's a complex area, and there's lots we still don't know, but studies of long-term outcomes of children who attended daycare generally don't provide any evidence of bad effects. I find Sigman’s extreme position unconvincing.’

Working parents feel guilty

The National Day Nurseries Association said that the debate around stress levels in children under three in daycare fails to take into account any of the positive benefits of childcare, such as studies showing that children in high quality nurseries are more likely to achieve more educationally and socially in later life.

Purnima Tanuku, chief executive of the NDNA, said, ‘Parents face many difficult decisions when balancing work and family life and it is unfair to suggest that nurseries are simply a lifestyle choice. In these difficult economic times, nurseries play an essential role in enabling families to return to work and survive financially.

‘Parents face conflicting advice about what is best for their children and unbalanced reports are unhelpful and make parents feel guilty about working when many children have a very positive experience at nursery.

She added, ‘Childcare is a fact of life for hundreds and thousands of parents and the real debate should be around how further support can be provided to increase the quality of childcare.’