Fatigue

Persistent physical and mental tiredness or exhaustion that is not relieved by rest. Most forms of fatigue ultimately stem from low or blunted cortisol output, even when they follow a period of chronic high cortisol 'overdrive.' In early stress phases, high cortisol and adrenaline can cause a wired, restless form of energy that feels powerful but depletes nutrients and suppresses recovery. As the HPA axis adapts or collapses, cortisol signaling falls, leading to true fatigue with low energy and poor stress tolerance. Nutrient deficiencies (e.g., vitamin C, B5, magnesium, sodium, cholesterol) can further weaken adrenal hormone synthesis and signaling.

• High cortisol (hyperactive HPA – overdrive phase): Cortisol and catecholamines mobilize fuel and blunt fatigue signals, creating a wired and strong feeling. However, prolonged activation depletes micronutrients, disrupts sleep, and accelerates mitochondrial wear, eventually leading to a crash.
• Low cortisol (hypoactive HPA – fatigue phase): Adrenal output and receptor sensitivity decline, impairing glucose release and ATP production. This results in persistent low energy, apathy, weakness, and difficulty handling stress.