Cortisol is one of the body’s major hormones that keeps daily functions running smoothly. While most people recognize cortisol for its stress-regulating role, it also helps control blood pressure, supports metabolism, and keeps inflammation in check.

Cortisol follows your internal body clock—known as the circadian rhythm—causing levels to naturally rise and fall across a 24-hour day.

When Cortisol Peaks

Morning rise in cortisol
In most people, cortisol reaches its highest point 30–45 minutes after waking up. This predictable surge—called the cortisol awakening response—can raise cortisol levels by 50% to 150%.
According to endocrinologists, the morning spike sharpens alertness, boosts energy stores, and helps the body transition from sleep into wakefulness.

Who may not experience this rise
Not everyone has a pronounced awakening response. The pattern can be disrupted in people who work overnight shifts or have chronic sleep interruptions. Research suggests approximately three-quarters of healthy adults show a typical cortisol rise in the morning.

How Cortisol Changes Throughout the Day

Afternoon decline
After peaking shortly after waking, cortisol gradually decreases. Many people notice the lowest point during mid-afternoon—often experienced as the “post-lunch slump.”

Lowest point overnight
Levels reach their minimum around midnight while the body is sleeping and repairing itself. Around 3 a.m., cortisol gradually begins rising again—resetting the daily rhythm for the next morning.

When Cortisol Spikes Outside the Daily Rhythm

Fight-or-flight response
Cortisol temporarily rises when you encounter stress—physical, emotional, or psychological. This survival response quickly mobilizes stored energy, giving your muscles and brain glucose and fatty acids to react to danger or pressure.

Immune activation
Cortisol can also increase when you are sick. Short-term rises help spark immune activity and inflammation needed to defend against infection.

When Cortisol Stays High Too Long

Chronic elevation
Long-term high cortisol may occur due to ongoing stress, steroid medications, or medical conditions such as Cushing’s syndrome. Over time, excessive cortisol may lead to noticeable physical changes, including:

  • Weight gain, especially around the midsection

  • Thin arms and legs

  • Rounded, fuller face

  • Fat accumulation behind the neck or between shoulder blades

  • Muscle weakness

  • Easy bruising

  • Wide purple stretch marks on the abdomen, thighs, or underarms

Anyone with these symptoms should speak with a healthcare provider about proper testing.

Supporting a Healthy Cortisol Rhythm

Lifestyle matters
Cortisol naturally fluctuates—and the daily peaks and lows are normal and important. Endocrinologists emphasize that getting consistent sleep, eating nutritious meals, managing stress, and regular movement support a healthy rhythm.

Know when to get help
Stress, illness, medications, or underlying conditions can shift cortisol levels outside a healthy range. If you suspect chronically high cortisol or have symptoms linked to hormonal imbalance, a medical evaluation is recommended.