Adrenaline and cortisol are steroid hormones that are released by the adrenal glands in response to HPA axis activation. The heart rate and energy levels are increased by these hormones. Synthesized pharmaceutical versions of cortisol can be used to treat conditions such as asthma.

Attunement is the process whereby parents are attentive or “tuned in” to the emotional experiences and needs of their children. Attunement allows parents to soothe or support children as the child needs, creating the conditions that promote secure attachment to this parent and, eventually, healthy self-regulation of their emotions.

Stress is a physiological reaction to pressure or threats in one’s environment. Citing Hans Selye, Maté notes that stress has three elements: the stressful event itself, the processing of the stressful event, and the response to the event. When the Body Says No focuses on the “response” component, which involves the activation of the central nervous system and the HPA axis, which is responsible for the secretion of hormones like cortisol and adrenaline. While stress serves an important evolutionary role in protecting people from life-threatening situations, a state of chronic stress—such as through the repression of emotion—can impact the body’s stress-response systems. For instance, people who experience chronic stress release less cortisol.