When it comes to stress and babies, the stakes may be even higher. Studies with rats and monkeys show that neglectful care, early in life, and lack of parental support when an infant is distressed, have a powerful influence on the development of stress response systems. If stressful conditions like these continue during early development, they may set in place a lifelong pattern for higher levels of stress hormones. Also, these studies show that living in a deprived environment with little personal contact and few things to see or touch can result in higher stress hormone levels. On the other hand, when little ones receive consistent, nurturing attention from caregivers and the opportunity to explore their world, they are more likely to develop healthy stress response systems (Gunnar, 2000).

It’s hard to conduct stress experiments on humans—especially children. Subjecting babies to parental neglect and threatening situations and then measuring the levels of their stress hormones is unthinkable. But in a study of children adopted from Romanian orphanages, where living conditions were harsh, researchers found that the longer a child lived under extreme conditions, the higher his or her stress hormones were, even six and a half years after adoption (Gunnar, Morison, Chisholm & Schuder, 2001).


To examine the effects of stress on children scientists studied three groups of children, all between 6 to 12 years old and living with families in western Canada. One group had been adopted after spending more than eight months of their early lives in orphanages. Members of the second group had been adopted from the orphanages when they were four months old or younger. Members of the third group were born in Canada and raised in their original families (Gunnar et al., 2001).

Parents took samples of their children’s saliva on three days when nothing unusual was scheduled: once in the morning, again at noon, and finally within a half-hour of bedtime. After analyzing the saliva samples, the scientists found that the children who spent more than eight months in orphanages had significantly higher average levels of cortisol than either the children adopted earlier in life or the Canadian-born children. And the longer the children had lived in orphanages, the higher their average levels of cortisol (Gunnar et al., 2001).

More research is needed before scientists can say for sure that living in stressful situations early in life causes children to have higher levels of stress hormones later on, or even that increased hormone levels always lead to health problems. But, the researchers noted, their results are consistent with studies in rats that point to a sensitive time in early development when the response to stress may be set (Gunnar et al., 2001).