The concepts of 'consumptive disease' and 'deficiency of yin-yang and qi and blood' in Donguibogam can be explained in modern medicine as an autonomic nervous system imbalance and dysfunction of the neuroendocrine system, which are our body's complex regulatory systems. Feeling tired even after sleeping is a signal that your 'sleep quality' has dropped severely, rather than simply having an insufficient quantity of sleep.
Our brain restores the body and mind through several stages of sleep (light sleep, deep sleep, REM sleep) during the night. In particular, during deep sleep (slow-wave sleep), where brain activity slows down, growth hormone is secreted so cell regeneration and tissue repair actively take place, immunity is strengthened, and brain waste accumulated during the day is removed in an important process. However, if this deep sleep stage is not sufficiently secured due to stress or irregular lifestyle habits, no matter how long you sleep, your body will not feel refreshed and fatigue will not be resolved.
The hypothalamic-pituitary-adrenal axis, which is our body's 'stress response system', and the autonomic nervous system significantly affect this decline in sleep quality. Chronic stress excessively activates the HPA axis and increases the secretion of the stress hormone cortisol, which induces arousal and disrupts sleep. If cortisol levels remain high at night when it is time to rest comfortably, entering deep sleep becomes difficult and sleep becomes centered on light sleep. Similar to the 'deficiency of yin energy' mentioned in Donguibogam, this means a state where the body cannot rest properly when it needs to rest.
In addition, the autonomic nervous system regulates biological functions regardless of our conscious will, such as heartbeat, digestion, respiration, and sleep, and is divided into the sympathetic nerve and parasympathetic nerve. The sympathetic nerve tenses the body and expends energy, as in the 'fight-or-flight response', while the parasympathetic nerve relaxes the body and stores energy, as in the 'rest-and-digest' response. Modern individuals often have an excessively activated sympathetic nerve due to heavy workloads, smartphone use, and competitive environments. If the sympathetic nerve maintains dominance even at night, the body fails to prepare for sleep and remains in a state of tension, hindering deep sleep. This aligns with the Donguibogam concept of 'consumption of qi and blood', causing a state where body energy is unnecessarily spent and cannot recover.
Furthermore, disruption in the secretion of the hormone melatonin, which induces sleep, or an imbalance in neurotransmitters such as serotonin can also cause a sleep disorder. Being exposed to bright lighting or smartphone screens late at night suppresses melatonin production, making it easy for biological rhythms to be disrupted. These complex factors act together to bring about a chronic decline in sleep quality where one is 'tired no matter how much sleep is had', and over the long term, this can lead to decreased immunity, an increased risk of chronic disease, and other issues.
