The HPA axis plays a central role in the body’s stress response:
1. Eustress:
In the case of eustress, the nervous system activates the sympathetic response, preparing the body for a short-term challenge. This activation leads to the release of stress hormones, albeit in moderate amounts. The result is increased alertness, energy, and motivation. Eustress promotes the release of neurotransmitters such as dopamine and norepinephrine, contributing to positive mood and a sense of control.
2. Distress:
In contrast, distress leads to excessive activation of the HPA axis. Chronic stress causes an overproduction of cortisol. High cortisol levels can disrupt the body’s feedback mechanisms by maintaining stress-related physiology even when the stressors are no longer present. This can lead to physiological and psychological consequences such as anxiety, depression, sleep disorders, and a variety of physical illnesses. Elevated cortisol levels are associated with inflammatory processes and a weakened immune system (McEwen, 2006).