Scientific studies have shown that caffeine does have the ability to elevate cortisol levels in the body. Cortisol is released as a result of stimulation of the HPA axis of the central nervous system. The HPA axis is a part of the neuroendocrine system that regulates many body functions, including the reaction to stress.
Habituation
Cortisol, the stress hormone, is released after consuming coffee whether you are under mental stress or not, according to a study published in February 2008 in "Psychosomatic Medicine." However, the cortisol response to caffeine depended on whether or not caffeine was consumed regularly by the participants. Cortisol levels were highest when caffeine was avoided for five days prior to consumption compared to those who drank it every day.
Psychosis
Caffeine-induced psychosis is explained by the elevation of cortisol caused by caffeine consumption, according to a study published in March 2009 in "Personality and Individual Differences." For example, a group of caffeine consumers who at the time had not been diagnosed with a psychotic disorder were found to have more hallucinations than non-caffeine consumers. The researchers found that the psychosis was not explained by an elevation of stress, but existed independent of stress level.
Process
Caffeine is considered a stimulant to the central nervous system, which is why it has the ability to increase cortisol levels in the body. When caffeine is consumed, the brain metabolizes nutrients faster, although blood flow is decreased. This is called hypoperfusion and has been associated with an imbalance of cortisol, according to a study published in 2010 in "Critical Care."
Differences
Caffeine-induced cortisol elevation was found to affect men differently than women, according to a study published in March 2006 in "Pharmacology Biochemistry and Behavior." Cortisol levels were increased the same in men as they were in women after consuming 250mg of caffeine three times a day. However, the researchers found that women had less mental stress than men as a result of the increased cortisol, indicating a gender differences in response to caffeine-induced cortisol increase.
References
- PubMed Central: Caffeine Stimulation of Cortisol Secretion Across the Waking Hours in Relation to Caffeine Intake Levels
- RefDoc: Caffeine, stress, and proneness to psychosis-like experiences: A preliminary investigation
- "Critical Care": Is cortisol the key to the pathogenesis of delirium after coronary artery bypass graft surgery?
- SciVerse: Cortisol responses to mental stress, exercise, and meals following caffeine intake in men and women
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