Re-examining the wisdom of Donguibogam through the lens of modern science reveals that tumultuous dreams and waking without feeling refreshed are deeply tied to complex interactions between the brain, hormones, and the nervous system.
Nightmares are known to occur primarily during the REM sleep stage. REM sleep is an important time when our experiences and emotions are processed and memories are consolidated. However, under severe emotional pressure such as excessive stress, anxiety, or trauma, the pattern of REM sleep itself can become unstable, leading directly to intense and distressing dreams—nightmares.
When placed under stress, our body secretes stress hormones such as cortisol and adrenaline. These hormones induce a fight-or-flight response, bringing the body into a state of arousal. If stress remains unresolved before going to bed and cortisol levels stay elevated, the production of melatonin, the sleep-inducing hormone, is disrupted, lowering overall sleep quality. Melatonin is a key hormone that regulates the sleep-wake cycle, and stress disrupts this melatonin secretion rhythm, making it difficult to fall into a deep sleep.
In addition, an imbalance in neurotransmitters can be a significant cause of nightmares and sleep disorders. Serotonin, known as the happiness hormone, is also a precursor to melatonin. When serotonin levels are low, sleep quality drops, and feelings of anxiety or depression increase, raising the likelihood of nightmares. A neurotransmitter called gamma-aminobutyric acid, or GABA, acts to suppress and calm brain activity, and when GABA is deficient, the brain becomes overly excited, making it hard to fall asleep and resulting in shallow sleep.
The autonomic nervous system also plays a major role. In our body, there are sympathetic nerves that increase heart rate and consume energy, and parasympathetic nerves that relax the body and conserve energy. The parasympathetic nerves must be activated before bedtime to allow for restful sleep. However, if sympathetic nerves remain heightened late into the night due to excessive work, smartphone use, or psychological pressure, our body perceives itself as being in a state of danger and cannot rest peacefully, eventually causing unstable sleep and nightmares.
Recent studies also view the gut-brain axis as influencing sleep. Because the gut microbiota is involved in producing various neurotransmitters, including serotonin, poor gut health can adversely affect sleep quality. As such, modern science clearly demonstrates that our nightmares are not merely matters inside our heads, but bodily signals comprehensively linked across the brain, hormones, the nervous system, and even gut health. The instability of the ethereal soul and spirit described in Donguibogam is effectively explained in modern science as a multifaceted physiological imbalance.
