While the Donguibogam described the kidney as deficient and cold, modern medicine examines nocturia through a more detailed lens. Interestingly, the underlying context remains very similar: it signals that the body's balance has been disrupted. Nocturia generally stems from two main causes. The first is nocturnal polyuria, where the volume of urine produced at night becomes excessively high. The second is nocturnal frequency, where reduced urinary bladder capacity leads to frequent urination. These two factors can also occur together. A primary contributor to nocturnal polyuria is abnormal secretion of antidiuretic hormone (ADH). ADH, which reduces urine volume during daytime hours, must be secreted in sufficient amounts at night so urine can concentrate and remain stored in the urinary bladder. With age, the pituitary gland's capacity to secrete ADH may decline, or the kidneys may become less responsive to it, causing continuous urine production through the night. Issues in the pituitary gland or certain medications, such as diuretics, can also alter ADH function. In addition, chronic diseases such as heart failure, kidney disease, and diabetes significantly disrupt fluid and electrolyte balance. In people with heart failure, fluid that pooled in the lower legs during the day redistributes toward the kidneys once lying down, commonly increasing nighttime urine output. Sleep apnea is another recognized cause. When blood oxygen levels drop during apnea episodes, the resulting strain on the heart triggers the release of atrial natriuretic peptide (ANP), which promotes the excretion of sodium and water and elevates nighttime urine production. The second cause, nocturnal frequency, is closely tied to the urinary bladder itself. Reduced bladder muscle elasticity, overactive bladder, urinary tract infections, and benign prostatic hyperplasia in men all decrease functional bladder capacity and lead to frequent urination. Weakening of the pelvic floor muscles also impairs urinary bladder control, making it harder to hold urine. What the Donguibogam described as coldness and deficiency of the kidney aligns closely with the hormonal imbalances, circulatory changes, and urinary bladder hypofunction recognized today. Nocturia that disturbs your sleep should not simply be brushed off as normal aging. Be sure to consult a healthcare professional to rule out any underlying medical conditions.
