Sequence and Seasonal Effects of Salivary Cortisol

Abstract

Assessments of cortisol levels in saliva have been widely used by both researchers and clinicians as an index of adrenal functioning. Quarterly measurements of morning and evening cortisol levels were determined in a longitudinal study of 147 participants (72 women and 75 men) followed for I year each. The analysis of salivary cortisol revealed no significant gender or age differences in the sample. There was a sequence effect in quarterly cortisol values with a progressive decrease in serial measurements, especially notable in the morning values, as well as a seasonal variation in cortisol levels with significantly higher levels found in winter and fall, compared with spring and summer. The findings in this study suggest that repeated saliva sampling and seasonal variation in cortisol levels may independently affect adrenal response and, therefore, need to be accounted for in longitudinal studies.

Index Terms:

• cortisol
• HPA axis
• season
• stress

Additional information

Notes on contributors

Jean A. King

Dr King and Ms Kelly are with the Behavioral Neuroscience Program of the Department of Psychiatry, University of Massachusetts Medical School. Drs Rosal, Ma, and Reed arc in the Division of Preventive and Behavioral Medicine, and Dr Ockene is in the Division of Cardiovascular Medicine, Department of Medicine. All are at the University of Massachusetts Medical School in Worcester. Dr Stanek is in the Department of Biostatistics and Epidemiology at the University of Massachusetts, Amherst.