Cardiovascular reactivity, mood, and task performance in deprived and nondeprived coffee drinkers.

Forty habitual, heavy coffee drinkers (M = 5.7 cups/day) participated in two experimental sessions. Participants were deprived of their morning coffee for one of the laboratory sessions, not deprived the other. During each session, subjects consumed 12 oz of caffeinated coffee, decaffeinated coffee, or caffeine-free herbal tea. Measurements of heart rate, blood pressure, mood, and catecholamine response to deprivation and consumption of the beverage, alone and in combination with challenging tasks, were made. This study found that caffeine continues to cause blood pressure increases with chronic, heavy consumption and that these effects do not appear to habituate with regular use. Subjects reacted to behavioral challenge with fewer negative mood effects if they had consumed caffeine or coffee. Mild caffeine deprivation was associated with symptoms of stress.