Looking at the wisdom of Donguibogam through the lens of modern medicine, the phenomenon of 'heart fire flaring upward' can be explained as a subtle imbalance in our autonomic nervous system and hormonal systems. Sleepless nights accompanied by a burning heart are deeply linked to excessive activation of the sympathetic nervous system. The sympathetic nervous system prepares the body to 'fight or flee' by increasing tension and mobilizing energy. When stress or anxiety persists, the sympathetic nervous system becomes overly aroused, accelerating the heart rate, raising blood pressure, tightening muscles, and elevating body temperature. In particular, the stuffiness and sensation of heat resulting from excessive blood circulation toward the head serves as the modern interpretation of this surging heat feeling.
Sleep finally arrives when the parasympathetic nervous system is activated, allowing the body to relax and stabilize. However, if the sympathetic nervous system runs rampant through the night, the brain remains in a continuous state of arousal, and the secretion of sleep hormones such as melatonin is suppressed. The amygdala in the brain is a core region responsible for fear and anxiety; when emotional instability persists, the amygdala overreacts and repeatedly regenerates anxious thoughts whenever you try to fall asleep. This triggers a vicious cycle that disrupts the function of the hypothalamus, which induces sleep, as well as the pineal gland, which is involved in melatonin secretion.
Furthermore, chronic stress elevates the secretion of the stress hormone cortisol. Normally, cortisol peaks in the morning and drops to its lowest level at night. However, when stress keeps cortisol levels elevated at night, the body perceives an 'emergency state', making it difficult to fall asleep. This can be viewed as equivalent to the 'heart fire' continuing to blaze without subsiding, as described in Donguibogam.
In addition, neurotransmitter imbalances significantly affect insomnia. Serotonin, known as the happiness hormone, is a precursor to melatonin, and gamma-aminobutyric acid (GABA), which helps stabilize the brain, also plays a crucial role in inducing sleep. Anxiety and stress disrupt the balance of these neurotransmitters, increasing brain excitation, hindering relaxation, and ultimately preventing deep sleep. A hot heart and sleepless nights are ultimately a powerful signal from your body and mind crying out for rest.
