Which lifestyle factors change Cortisol?

Cortisol, the primary glucocorticoid, is modulated by several lifestyle factors. The strongest evidence links sleep deprivation: even one night of less than 6 hours elevates evening cortisol and disrupts circadian rhythm. Chronic psychosocial stress (e.g., work overload, social isolation) dysregulates the HPA axis, often resulting in elevated fasting cortisol or a flattened diurnal slope. Intense endurance exercise transiently raises cortisol, whereas moderate activity tends to lower stress responses. Diet also matters: high glycemic load, caffeine, and alcohol acutely increase cortisol; a balanced, fiber-rich diet with adequate omega-3s appears protective. Morning light exposure supports a healthy cortisol awakening response. Mindfulness practices and social support reliably reduce stress reactivity. Caveat: consumer tests measuring a single cortisol point from saliva or blood are unreliable due to strong diurnal variation and individual differences. Suspected adrenal dysfunction requires clinical evaluation with multiple measurements (e.g., dexamethasone suppression test). Evidence is strong for sleep and stress, moderate for exercise and diet, and mechanistic for light and mindfulness.