When cortisol stays high for too long, the brain can shift into a heightened state of alertness. The amygdala becomes more reactive, scanning for risk and pulling attention toward anything that feels even slightly uncertain. A neutral message, a tight deadline or an offhand remark can feel far more threatening than it is.

At the same time, elevated stress is described as reducing the effectiveness of the prefrontal cortex. This is the region that helps with steady thinking, emotional regulation and perspective. When it is under strain, it becomes harder to stay calm, weigh situations clearly or keep small issues in proportion. Black and white thinking and rapid emotional swings can feel more common.

High cortisol can also disrupt the natural rise and fall of sleep-related hormones. If levels remain elevated late in the day, melatonin may be suppressed, making it harder to fall asleep or stay asleep. Poor rest then feeds back into greater sensitivity and lower resilience.

Together, these patterns can make people feel tense, less clear headed and quicker to react on instinct rather than intention. Practices that support the parasympathetic nervous system can be helpful for restoring balance and rebuilding resilience.