Caffeine Stimulation of Cortisol Secretion Across the Waking Hours in Relation to Caffeine Intake Levels
William R. Lovallo, PhD,
Thomas L. Whitsett, MD,
Mustafa al’Absi, PhD,
Bong Hee Sung, PhD,
Andrea S. Vincent, PhD and
Michael F. Wilson, MD
From the Veterans Affairs Medical Center (W.R.L., A.S.V., B.S.M., T.L.W.), Department of Psychiatry and Behavioral Sciences (W.R.L., A.S.V.), and Department of Medicine (T.L.W.), University of Oklahoma Health Sciences Center, Oklahoma City, OK; Department of Behavioral Sciences (M.A.), University of Minnesota Medical School, Duluth, MN; Cardiology (M.F.W., B.H.S.), Kaleida, Millard Fillmore Division, Buffalo, NY.
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Figure 1. Caffeine concentrations in saliva on 4 test days. Entries show means, and error bars represent standard errors. Samples from 7:30 AM to 2:00 PM were collected in the laboratory, and the samples at 6:00 and 7:00 PM were collected at home. PC = placebo maintenance followed by 3 x 250-mg caffeine challenges on the test day. C300 = 300 mg/day of caffeine at home followed by caffeine challenge on the test day. C600 = 600 mg/day at home followed by caffeine challenge on the test day. PP = placebo at home and placebo on test day. Base 1, Base 2, Base 3 = saliva samples taken immediately before taking a caffeine or placebo capsule. PostC = samples taken 1 hour postdrug. Stress and Recov = samples taken at the end of a 30-minute behavioral stress period or after 30 minutes of recovery.
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Figure 2. Cortisol concentrations in saliva on 4 test days. Entries show means and standard errors. Abbreviations, sampling times, and designations as in Figure 1. Numbers above error bars refer from top to bottom to p values of PC, C300, and C600 week contrasts against the PP week control value.
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Copyright © 2005 by the American Psychosomatic Society
