The fatigue, pessimism, and lack of motivation we experience when sick is an evolved program called "sickness behavior." It's not just a passive result of the illness but an active, adaptive strategy to conserve energy, hide from predators, and focus bodily resources on fighting infection.
Chronic low-grade inflammation often presents not as obvious swelling but as subtle, persistent symptoms. Issues like increased fatigue, difficulty concentrating, poor sleep, and skin problems can be driven by an under-the-radar inflammatory state that even doctors may miss.
Evolution shaped mood to manage energy investment. Positive mood encourages us to double down when pursuits are rewarding. Conversely, low mood acts as a brake, preventing us from wasting energy on unpromising ventures. This reframes it as a strategic withdrawal rather than a simple malfunction.
Life operates on a finite energy budget divided between vital functions, stress responses, and growth/maintenance/repair (GMR). Energy allocated to stress is directly diverted from GMR, meaning chronic stress actively prevents your body from healing, repairing, and growing.
The evolutionary "fight or flight" response floods the body with hormones like cortisol to handle immediate threats. This life-saving mechanism comes at a cost: it diverts resources away from non-essential functions like digestion. Chronic stress therefore leads to a chronically sacrificed and weakened gut.
The temporary feeling of depression after a vaccine is a direct physiological response. The immune system's activation sends inflammatory signals to the brain, mimicking the biological state found in chronic depression and suggesting an immune basis for mood disorders.
Contrary to popular wellness narratives, denial can be a productive short-term response to trauma. It's nature's way of letting in only as much pain as we can handle, providing a sense of control and hope when we need it most to remain resilient.
Contrary to the dominant medical model, mental health issues like depression and anxiety are not illnesses. They are normal, helpful responses that act as messengers, signaling an underlying problem or unresolved trauma that needs to be addressed rather than a chemical imbalance to be suppressed.
Cytokines, the molecules of inflammation, are essentially distress signals from cells that are struggling energetically. For example, the cytokine IL-6 released after intense exercise is the muscle's way of signaling it needs energy mobilized from other parts of the body.
We often assume our thoughts cause our feelings. However, the body frequently experiences a physical state first (e.g., anxiety from adrenaline), and the conscious mind then creates a plausible narrative to explain that feeling. This means the "reason" you feel anxious or unmotivated may be a story, not the root physical cause.
The fatigue, apathy, and loss of appetite you feel when sick are not just passive symptoms. They are an evolved, intelligent response to conserve energy by shutting down non-essential processes (like digestion and motivation) to redirect that energy budget to fight infection.