"What Did I Do Yesterday?" When Your Whole Body Aches for No Reason, It Is Your Body's SOS Signal

In modern medicine, aching and stiff feelings throughout the body for no apparent reason can be explained as stress-induced muscle pain or generalized myalgia caused by overwork. When placed under stressful conditions, our body initiates a fight-or-flight response. The sympathetic nervous system becomes activated, secreting stress hormones such as adrenaline and cortisol. While these hormones temporarily boost energy by tensing muscles and constricting blood vessels, problems arise when this state becomes chronic.

Prolonged muscle tension reduces microvascular blood flow within the muscles. When blood supply decreases, the delivery of oxygen and nutrients to muscle cells is compromised, and fatigue substances like lactic acid along with inflammatory markers begin to accumulate. These substances stimulate nociceptors within the muscles, causing stiffness, aching, and pain. Furthermore, stress influences the brain's pain perception system. Ongoing stress alters the brain's pain-modulating pathways, making one perceive pain more sensitively even to minor stimuli. This is called central nervous system sensitization, a state where one feels chronic pain even without actual tissue damage.

In addition, sleep deprivation is a major culprit that worsens muscle pain. Sleep is an essential time for repairing damaged muscles and strengthening the immune system. If sleep is insufficient, muscle recovery slows down, inflammatory responses become more active, and pain can worsen. Stress and overwork also affect the brain-endocrine-immune axis to trigger a systemic inflammatory response, which can manifest as muscle pain throughout the body. Just as Donguibogam states that muscles weaken when qi and blood are deficient, modern medicine also sees that stress and overwork disrupt the whole-body biological rhythm, lowering muscle resilience and causing pain. Now you can see that a complex physiological response lies beneath what cannot be fully explained by simply saying one is tired.