Coffee versus Caffeine: Effects on Subjective and Behavioral Measures of Alertness
Abstract
This research was designed to address two main hypotheses. First, that coffee ingested by regular coffee drinkers has subjective and behavioral effects beyond those attributable to caffeine. And second, that caffeine presented in coffee produces different subjective and behavioral effects than caffeine presented in a novel beverage. Examination of the hypotheses was accomplished by crossing beverage (coffee versus non-caffeinated herbal tea) with caffeine content (0 versus 200 mg), thus exposing subjects to coffee with and without caffeine, and caffeine with and without coffee. Forty-eight coffee drinkers and 10 non-coffee drinkers participated in the study. Non-coffee drinkers were exposed only to the non-caffeinated herbal tea, and served as control subjects. Subjects participated in a single morning session, following overnight abstinence. Blood pressure, heart rate, mood and caffeine withdrawal-related symptoms, as well as performance on an auditory vigilance task, were measured before and after beverage administration. Subjects and experimenter were blind to the caffeine content of the beverage. Caffeine was associated with an increase in diastolic and systolic blood pressure, and a decrease in heart rate. Caffeine was also associated with more positive affect, fewer withdrawal related symptoms, and enhanced performance over time. Coffee, with or without caffeine, was found to ameliorate withdrawal-related headache and desire for a stimulant. Both coffee and caffeine were associated with better performance over time compared to the non-caffeinated herbal tea. Caffeine presented in a novel beverage was not found to affect subjective or behavioral measures differently than caffeine presented in coffee.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 12, 1991
- Accession Number
- AD1011023
Entities
People
- Mary K. O'keeffe
Organizations
- Uniformed Services University of the Health Sciences