Cortisol is a hormone produced by the adrenal glands, small organs located atop the kidneys. While commonly associated with the body’s response to stress, cortisol performs many functions beyond managing fight-or-flight reactions. This hormone helps regulate how the body uses energy from food, influences blood pressure, and plays a role in reducing inflammation. Cortisol also participates in controlling the sleep-wake cycle.
The Normal Daily Cortisol Graph
A healthy body follows a natural, predictable pattern of cortisol release throughout a 24-hour period, known as its circadian rhythm. Cortisol levels reach their highest point shortly after waking in the morning. This sharp increase is referred to as the Cortisol Awakening Response (CAR) and prepares the body for the day’s activities.
Following this morning peak, cortisol levels gradually decline throughout the day. The hormone reaches its lowest concentrations around midnight, facilitating the transition into sleep. Graphically, this healthy pattern appears as a distinct peak in the early morning, followed by a steady downward slope through the afternoon and evening hours. This rhythmic fluctuation is important for maintaining energy, alertness during the day, and promoting restful sleep at night.
Abnormal Cortisol Graphs and Their Causes
Deviations from the typical daily cortisol pattern can indicate underlying health imbalances. One common abnormality is chronically high cortisol, where levels remain elevated throughout the day without the expected decline. This pattern can result from prolonged psychological or physical stress, insufficient sleep, or medical conditions such as Cushing’s syndrome. In Cushing’s syndrome, an overproduction of cortisol often stems from a tumor.
Another distinct pattern is chronically low cortisol, which appears as a flat line on a graph, with consistently diminished levels throughout the day. This can be associated with Addison’s disease, a rare condition where the adrenal glands are damaged, often by an autoimmune response. While sometimes referred to as “adrenal fatigue,” low cortisol is more accurately understood as a dysregulation within the hypothalamic-pituitary-adrenal (HPA) axis, which regulates the body’s stress response.
A blunted or reversed cortisol rhythm presents as a graph lacking the characteristic sharp morning peak, or even showing lower levels in the morning that rise towards the evening. This altered pattern suggests HPA axis dysfunction, which can stem from long-term stress leading to burnout or significant disruptions to the sleep cycle. For instance, chronic sleep deprivation or shift work can interfere with the body’s natural clock, potentially leading to elevated evening cortisol levels and a flattened morning response.
Testing Methods for Cortisol Graphing
To visualize a person’s daily cortisol curve, healthcare providers often use a multi-point salivary cortisol test. This non-invasive method involves collecting saliva samples at several specific times throughout the day, such as immediately upon waking, 30 minutes after waking, around noon, in the late afternoon, and before bedtime. These multiple samples allow for mapping the hormone’s fluctuations over 24 hours.
Blood tests for cortisol are also available, typically taken once or twice a day. While useful for measuring cortisol at specific moments, they may not fully capture the dynamic daily rhythm and can be influenced by the stress of the blood draw itself. Twenty-four-hour urine tests measure the total amount of cortisol excreted over a full day, providing an overall average, but do not illustrate the hourly variations in cortisol levels.