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Why Kids Should Be Protected from Toxic Stress

Sustained stress has negative effects on child wellbeing

*First author is Kallie Renfus, with assistance from Angela Kurth

Have you noticed children who suddenly shift into heightened emotion? Their self-regulation systems have not been developed properly.

Children’s self-regulatory systems are under construction in early life. Children need parents to learn self-control and deal with stress. They need caregivers to help them calm down quickly so the stress-reactive systems don’t learn to habitually “stay on.” When parents act as if babies should calm themselves down, they are potentially setting up toxic stress for the baby. Instead, parent responsiveness and quick calming of baby systems helps the baby to learn to calm herself down over the first few years of life.

The stress response refers to what happens when a person senses threat. The stress response has two major response patterns: “fight or flight” or “freeze-faint.”

Under perceived threat, the body mobilizes energy to “fight-flight-freeze-or-faint” (moving from to the next until one works). Fight or flight is a reaction in the sympathetic nervous system that activates the body and increases blood flow, preparing the body to take action (Perry, 2014). This works very well for zebras (and other animals), helping them use the energy to escape or fight off predators. Because zebras mobilize the stress response only occasionally in reaction to predators, after the burst of excitement their stress systems are able to calm down and return to a normal baseline. So, “zebras don’t get ulcers” (Sapolsky, 2004).

When fight-flight does not work --i.e., the zebra is “cornered”-- the parasympathetic system becomes activated, exhibited in freeze or faint responses. The body goes into survival mode, decreasing heart rate and slowing growth. First there is paralysis, then if things get worse, the individual faints in hopes that simulated death will prevent real death.

In infants facing stress, the freeze-faint (active dissociation) is common because crying doesn’t work and they are unable to run away. So an isolated baby who is quiet is not necessarily a good thing.

Sometimes babies live in chronically stressful environments. Chronic stress can turn into toxic stress, damaging all sorts of systems in the brain. Once a tolerance to a chronically stressful environment is built up, only a tiny dose, the theoretical “straw that breaks the camel’s back” can raise stress levels significantly and the child goes out of control (Perry, 2014). Niehoff (1999) describes the results of ongoing stress, which in older children and adults can look like deficient moral character but is overwrought physiology:

  • “As stress wears away at the nervous system, risk assessment grows less and less accurate. Minor insults are seen as major threats. Benign details take on a new emotional urgency. Empathy takes a back seat to relief from the numbing discomfort of a stress-deadened nervous system. Surrounded on all sides by real and imagined threats, the individual resorts to the time-honored survival strategies: Fight, flight, or freeze.” (p. 185)

For those dealing with excess stress, a return to a calm baseline becomes impossible. Why? Because the baseline has moved to over- or under-arousal. When a child is exposed to excess stress in early life, a predictably threatening world, the child stays always “on guard.” In this state, the slightest “straw” leads to an extreme reaction (Perry, 2014). This is unlike what happens with a child who has responsive caregivers who help the child develop secure attachment and good self-control systems through holding, rocking, and other calming reactions.

If a child is chronically exposed to stress, the stress response is overwhelmed and small stressors become challenging according to Bruce Perry.

What is chronic stress for a baby? Chronic stress occurs when parents let babies cry, make babies sleep alone, isolate them from touch (holding and carrying) and limit social play. (Read more: Ten Things Everyone Should Know About Babies, Dangers of “Crying It Out”.)

What happens to those with a sensitized stress response when they grow up?

According to research on Adverse Childhood Experiences (ACES) with children, those who had adverse experiences were five to ten times more likely to have ill health in adulthood (Perry, 2014).

What can parents do to prevent sensitized stress systems? Follow the baby. The baby tells you what it needs which is mostly close holding, skin-to-skin contact, rocking and feeding on the infant’s schedule. A supportive relationship with a caregiver contributes to the formation of resiliency skills against stress (Perry, 2014).

What can be done for children who have a sensitized stress system? Children’s brains are flexible as they are growing and developing. Strong supportive relationships can play a key role in shaping the brain throughout childhood. Find ways that calm stress in that child. For example, parents can help older children calm down with things as simple as tone of voice, supportive word or kind touch. These can go a long way.

Throughout life, healthy relationships can help to guide children in stress response, in finding ways to respond actively to stress, and in reducing the stress in a child’s life. Keeping away from toxic stress and finding ways to calm down decrease the likelihood of ill health later.


Perry, B. (September, 2014). The Biology of Trauma and Recovery. Pathways to Child Flourishing conference, University of Notre Dame.

Sapolsky, R. (2004). Why zebras don’t get ulcers, 3rd ed. New York, NY: Holt.

For more on parenting, stress response and adult morality, see new book, Neurobiology and the Development of Human Morality: Evolution, Culture and Wisdom.


1. Kindness in Kids and the Nature-Nurture Debate (Dr. Sarina Saturn)

2. Why Synchronize and Bond With Your Children (Dr. Ruth Feldman)

3. “I want it—now!” How Children Learn Self-Control (Dr. Julie Braungart-Rieker)

4. Why Kids Should Be Protected from Toxic Stress (Dr. Bruce Perry)

5. “Mr. Mom” The Old Normal (Dr. Lee Gettler)

6. Why Dad’s “Talk” is Important (Dr. Holly Brophy-Herb)

7. Conflict in the Family: Why Mom and Dad Should Say “Sorry” (Dr. Mark Cummings)

8. Domination or Partnership? How Does Your Family Stack Up? (Dr. Riane Eisler)

9. Why Carefully Invest Daily in a Child (Dr. Robin Nelson)

*Posts are based on talks presented at the Pathways to Child Flourishing conference, University of Notre Dame, Notre Dame, IN.



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When I write about human nature, I use the 99% of human genus history as a baseline. That is the context of small-band hunter-gatherers. These are “immediate-return” societies with few possessions who migrate and forage. They have no hierarchy or coercion and value generosity and sharing. They exhibit both high autonomy and high commitment to the group. They have high social wellbeing. See comparison between dominant Western culture and this evolved heritage in my article (you can download from my website):

Narvaez, D. (2013). The 99 Percent—Development and socialization within an evolutionary context: Growing up to become “A good and useful human being.” In D. Fry (Ed.), War, Peace and Human Nature: The convergence of Evolutionary and Cultural Views (pp. 643-672). New York: Oxford University Press.

When I write about parenting, I assume the importance of the evolved developmental niche (EDN) for raising human infants (which initially arose over 30 million years ago with the emergence of the social mammals and has been slightly altered among human groups based on anthropological research).

The EDN is the baseline I use for determining what fosters optimal human health, wellbeing and compassionate morality. The niche includes at least the following: infant-initiated breastfeeding for several years, nearly constant touch early, responsiveness to needs so the young child does not get distressed, playful companionship with multi-aged playmates, multiple adult caregivers, positive social support, and soothing perinatal experiences.

All EDN characteristics are linked to health in mammalian and human studies (for reviews, see Narvaez, Panksepp, Schore & Gleason, 2013; Narvaez, Valentino, Fuentes, McKenna & Gray, 2014; Narvaez, 2014) Thus, shifts away from the EDN baseline are risky and must be supported with longitudinal data looking at wellbeing in children and adults. My comments and posts stem from these basic assumptions.

My research laboratory has documented the importance of the EDN for child wellbeing and moral development with more papers in the works see (my Website to download papers):

Narvaez, D., Gleason, T., Wang, L., Brooks, J., Lefever, J., Cheng, A., & Centers for the Prevention of Child Neglect (2013). The Evolved Development Niche: Longitudinal Effects of Caregiving Practices on Early Childhood Psychosocial Development. Early Childhood Research Quarterly, 28 (4), 759–773. Doi: 10.1016/j.ecresq.2013.07.003

Narvaez, D., Wang, L., Gleason, T., Cheng, A., Lefever, J., & Deng, L. (2013). The Evolved Developmental Niche and sociomoral outcomes in Chinese three-year-olds. European Journal of Developmental Psychology, 10(2), 106-127.

Also see these books for selected reviews:

Evolution, Early Experience and Human Development (Oxford University Press)

Ancestral Landscapes in Human Evolution (Oxford University Press)

Neurobiology and the Development of Human Morality: Evolution, Culture and Wisdom (W.W. Norton)

More from Darcia F. Narvaez Ph.D.
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