Many people worry that traumatic material on social media, such as material with suicide or self-harm content, may be especially harmful for young people—and research suggests this concern is justified. During adolescence, the brain is still developing, particularly the systems involved in emotional regulation. At the same time, major hormonal changes are taking place. One of the most important hormones in this process is cortisol, which is released as part of the stress response. Changing cortisol levels during development help explain why teenagers may react more strongly to online traumatic content compared with adults. The stress response triggered by a traumatic incident or image involves activation of the brain’s amygdala. In turn, the amygdala activates the the hypothalamus, pituitary gland, and adrenal gland (HPA axis), which eventually leads to the release of cortisol from the adrenal gland1. This state persists until the cortex (through the prefrontal cortical structures) downwardly regulates (puts the brakes on) the amygdala, and stops the HPA cascade1. In the early stages of the response, the cortisol release actually helps the brain’s …