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. Author manuscript; available in PMC: 2008 Feb 27.
Published in final edited form as: Psychosom Med. 2005;67(5):734–739. doi: 10.1097/01.psy.0000181270.20036.06

Figure 1.

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 × 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.