Figure 3

Self-reported energy and sleepiness levels on continuous and binary scales over four hours after intervention. A and B: Time course of estimated unadjusted total effect (closed diamond), drug effect (closed squares), placebo effect (closed triangles), and interaction effect (closed circles with interrupted line) on VAS scores of energy and sleepiness level, respectively. C and D: Mean unadjusted VAS Scores for energy and sleepiness, respectively. E and F: Mean unadjusted percentage of time, lack of energy and sleepiness, respectively, were reported. T bars indicate standard errors. Squares indicate receiving 300 mg caffeine, described as caffeine (open square with continuous line) or as placebo (closed square with interrupted line) by 83 subjects in a balanced randomized cross-over design. Triangles indicate receiving placebo described as placebo (open triangle with continuous line) or as caffeine (closed triangle with interrupted line) by 85 subjects in a balanced randomized cross-over design. The difference between open squares and open triangles represents the total effect. The difference between closed squares and open triangles represents the drug effect. The difference between open triangles and closed triangles represents the placebo effect. The difference between open squares and closed squares represents the placebo+interaction effect.