From the perspective of modern medicine, what Donguibogam describes as weakness of the liver and spleen and fright and restlessness is deeply related to an infant's immature brain development. In particular, separation anxiety where a baby seeks mother at night is a normal developmental process commonly seen between 6 months and 3 years of age. However, if this leads to infantile night crying with nightly disrupted sleep and crying spells, it degrades sleep quality not only for the baby but also for the parents, affecting the health of the entire family.
The anxiety a baby feels when leaving mother's embrace to sleep alone is closely linked to the brain's limbic system. The limbic system is the region responsible for emotion, memory, and motivation, and the amygdala in particular is the key area processing emotions such as fear and anxiety. Because an infant's brain is still developing, the frontal lobe functions that regulate emotions are immature. Therefore, when fear of unexpected sounds, light, or unfamiliar environments arises, the amygdala becomes activated, causing intense feelings of anxiety. When the unfamiliar environment of nighttime combines with separation from mother, the baby's awareness of being alone sharpens, maximizing this anxiety.
This anxiety stimulates the secretion of cortisol, our body's stress hormone. Elevated cortisol levels increase heart rate and quicken breathing, priming the body to respond to danger at any moment. If cortisol levels remain high before or during sleep, it becomes difficult for the baby to enter deep sleep, causing frequent awakenings and crying spells at the slightest stimulation. Conversely, warm physical touch and secure attachment with mom stimulate the release of oxytocin, a hormone that enhances love and bonding. Oxytocin helps lower anxiety and enhances psychological stability, assisting the baby in falling asleep comfortably.
Furthermore, an infant's sleep architecture differs from that of adults, featuring much longer periods of light sleep. With substantial REM sleep and an immature transition process into non-REM sleep, night waking occurs frequently. When the psychological factor of separation anxiety is added to this, waking from light sleep and realizing mom is not beside them brings even greater anxiety, resulting in crying. In the end, a baby's infantile night crying is not merely due to hunger or discomfort; it can be understood as a phenomenon created by a complex combination of immature brain development, stress hormone effects, and the formation of secure attachment with mother. A warm, scientific approach is needed so that the baby can ease anxiety and achieve deep sleep independently.
