The exhaustion of the 'heart' described in Donguibogam corresponds in modern medicine to complex fatigue across the brain, autonomic nervous system, and endocrine pathways. Chronic stress and mental overload lead to hyperactivation of the hypothalamic-pituitary-adrenal axis, the brain's central stress response pathway, producing an imbalance in stress hormones such as cortisol.
While the body resists stress early on, prolonged strain leads to adrenal gland dysfunction, bringing chronic fatigue, lethargy, and declines in memory and concentration. The 'spirit' and 'consciousness' governed by the Donguibogam's 'heart' correspond in modern neurology to frontal lobe function, including cognitive control, decision-making, and planning. When frontal lobe activity declines, clarity of thought diminishes, judgment weakens, and motivation tends to drop.
Imbalances among neurotransmitters in the brain also play a significant role, including serotonin for well-being, dopamine for motivation and reward, and norepinephrine for alertness. Chronic fatigue depletes these neurotransmitters, deepening depression, anxiety, and lethargy. At the cellular level, mitochondria dysfunction, which impairs cellular energy production, is also recognized as a key contributor to chronic fatigue. When mitochondria cannot function properly, cells fail to generate adequate energy, allowing fatigue to build throughout the body.
Autonomic nervous system imbalance is equally important. Under sustained stress, sympathetic nerve hyperactivation keeps the body in continuous tension, while the parasympathetic nerve responsible for rest and recovery cannot function properly. This makes falling asleep at night difficult and leaves the body heavy and stiff during the day, preventing the brain from resting and frequently leading to burnout syndrome. An exhausted 'heart' can thus be understood as an overall fatigue signal issued by the interconnected systems of the brain and body.
