This double-blind, placebo-controlled, within-subjects (N = 18) experiment
compared the sensitivity to change of cognitive performance and mood measures
of mental energy following consumption of either 100 or 200-mg caffeine or a
440-calorie breakfast. Breakfast and 200-mg caffeine improvedmood and cognitive
performance. The sensitivity to change of the measures did not differ in response
to any treatment (all p values > .05). The mood and cognitive measures of mental
energy used here have similar sensitivity to detecting change in response to a
moderate dose of caffeine and breakfast consumption.