Imagine that you see a bear while walking through a forest. In response to this threat, your body switches into “fight or flight” mode. To survive, your body releases emergency stress hormones, like adrenaline and cortisol, that cause your heartbeat to quicken, make your eyes dilate and focus your mind on the threat at hand—everything you need to get your body ready to run or to fight back. When activated occasionally, this system bypasses our thinking brain—the prefrontal cortex—and activates the primitive reactions that can get us out of the way of a mortal threat. In situations like this, stress is helpful—it keeps you alive.
The problem comes when our system is overtaxed by repeated, intense or chronic stress. That cascade of chemicals and reactions goes from saving one’s life to damaging one’s health. Children are especially vulnerable to the harmful effects of chronic stress and trauma. For many kids who are repeatedly exposed to Adverse Childhood Experiences, such as violence at home or in the community, or having a parent with mental illness or substance dependence, their “fight or flight” system is activated so often that it stays on. These high levels of emergency hormones can lead to changes in the structure and function of children’s developing brains and bodies. The result is toxic stress.