How do stress types differ physiologically?

Different types of stress create different patterns in your physiology; acute stress has an immediate effect that activates the SAM axis, but this effect will resolve quite quickly; episodic stress has repeated surges of activity through the HPA axis, with cumulative effects; chronic stress creates a prolonged elevation in cortisol that leads to dysregulation throughout each of the physiological systems.

The SAM axis is responsible for acute stress. Within about 15 seconds, your adrenal medulla saturates your system with catecholamines. Your heart rate increases by 40-60 beats per minute immediately. Blood is directed to your major organs. Your breathing quickens and becomes shallow. You return to baseline within two hours.

Episodic stress. The cumulative effect of stressor after stressor. Your body doesn't drop back to baseline between stress spikes (it can't). Cortisol is firing on old trends multiple times a week. Inflammatory markers, such as CRP, are slowly trending upward. Your blood pressure baseline is gradually increasing over weeks of multiple stress spikes (see the bumpy graph, with at least one spike). Your muscle tension patterns become more entrenched.

Doing chronic stress? Welcome to allostatic load, the price that chronic stress extracts from your stress response. Cortisol hangs above at 20 μg/dL for months. Your HPA axis no longer self-regulates appropriately. You're damaged from many angles: immune system suppressed, hormonal storyline toxically muddled, blood vessels strained, neurons remodeled. You need serious intervention.

Read the full article: Understanding Stress Physiology: Body Responses