How does modern science explain the 'instability of heart and spirit' described in Donguibogam? Surprisingly, the context closely resembles facts revealed by modern neurology, endocrinology, and sleep science. Being unable to sleep late into the night with a cluttered mind happens because our body's autonomic nervous system mistakenly perceives an emergency. Originally, sleep comes in a state where the parasympathetic nervous system takes dominance and the body and mind relax, but excessive stress or thoughts overly stimulate the sympathetic nerve, keeping the body in a state of arousal. It is just like an engine continuously running at high RPM.
If this condition persists, the hypothalamic-pituitary-adrenal axis, the core axis regulating our brain's stress response, becomes hyperactivated. Stress hormones such as cortisol secreted here suppress the secretion of melatonin, which induces sleep, keeping the brain awake. According to research, patients with chronic insomnia tend to show higher cortisol levels before falling asleep than normal individuals. That is not all. Imbalances in neurotransmitters within the brain also exert a major influence. When serotonin, the happiness hormone that plays an important role in sleep regulation, is deficient, or the function of gamma-aminobutyric acid, which reduces anxiety, declines, we easily become anxious and caught in cascading thoughts. In terms of brain waves, alpha waves should increase before falling asleep to enter a relaxed state, but for those suffering from wandering thoughts, beta waves representing an aroused state remain continuously dominant.
In particular, 'wandering thoughts' and 'excessive thinking' can be explained in modern neurology as rumination or cognitive overload. As the frontal lobe, especially the medial prefrontal cortex and related networks, become overly active, a pattern appears of continually chewing over past negative experiences or incessantly worrying about future uncertainties. Such cognitive activity increases brain energy consumption and hinders the transition into true rest.
Here, the wisdom of Donguibogam, Shenmen (HT7), draws attention once again. Shenmen (HT7) is the yuan-source point of the heart meridian of hand shaoyin, which can be interpreted modernly as being deeply involved in autonomic nervous system balance. Research findings report that stimulating this acupoint may help activate the parasympathetic nervous system and suppress the hyperactivation of the sympathetic nerve. For example, the vagus nerve is the core of the parasympathetic nervous system, lowering heart rate, aiding digestion, and inducing overall relaxation; stimulation of Shenmen (HT7) is estimated to indirectly help activate this vagus nerve. In other words, what Donguibogam described as 'soothing the spirit' can be interpreted in modern scientific terms as 'restoring autonomic nervous system balance to switch the body and mind into true rest mode'. On sleepless nights, isn't it time to borrow both the wisdom of science and the wisdom of Korean medicine?
