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Published on: June 18, 2014
Individual differences in the diurnal cycle of cortisol
J M Smyth1, M C Ockenfels, A A Gorin
1Department of Psychiatry, State University of New York, Stony Brook 11794-8790, USA.
Psychoneuroendocrinology
|February 1, 1997
Summary
This study found that 17% of healthy adults lacked typical diurnal cortisol patterns. Surprisingly, individuals without these cortisol cycles reported fewer upper-respiratory illness symptoms.
Area of Science:
- Endocrinology
- Psychoneuroimmunology
- Health Psychology
Background:
- The diurnal cortisol cycle is a fundamental aspect of endocrine function.
- Cortisol levels are linked to stress, depression, and other psychosocial factors.
- The relationship between cortisol diurnal patterns and health outcomes, like illness symptoms, is not fully understood.
Purpose of the Study:
- To investigate individual differences in the diurnal cortisol cycle.
- To explore the association between cortisol diurnal patterns and psychosocial variables.
- To examine the relationship between cortisol diurnal patterns and upper-respiratory illness (URI) symptoms.
Main Methods:
- Cortisol levels and daily experiences were assessed over two days in 109 healthy adults.
- Self-report URI symptoms were collected for an additional ten days.
- Participants were categorized based on their cortisol diurnal patterns: typical, absent, or inconsistent.
Main Results:
- Fifty-one percent of participants exhibited typical diurnal cortisol declines on both days.
- Seventeen percent showed no significant diurnal cortisol pattern on either day (flat cycles).
- Individuals with flat cortisol cycles reported significantly fewer URI symptoms compared to those with normal or inconsistent cycles.
Conclusions:
- A notable proportion (17%) of healthy adults may not display typical diurnal cortisol cycles.
- Cortisol diurnal pattern, unlike average daily levels, was not associated with demographic or psychosocial factors in this sample.
- The unexpected finding of fewer URI symptoms in individuals with flat cortisol cycles suggests a potential role in symptom susceptibility or expression.
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