A randomized controlled trial was employed in which participants were randomly allocated to either an experimental group (n=15) or a control group (n=17) using a computer generated random number table. Treatment allocation was concealed in opaque envelopes. Decaffeinated plunger coffee with 100 mg caffeine for the experimental group and decaffeinated plunger coffee for the control group was prepared from two single identical packs of coffee with the same taste.