Sensitivity to change in cognitive performance and mood measures of energy and fatigue in response to morning caffeine alone or in combination with carbohydrate.

This double-blind, placebo-controlled, within-subjects (N = 17) experiment compared the sensitivity to change of the cognitive performance and mood measures of mental energy following consumption of either a moderate dose of caffeine (200 mg), a small amount of carbohydrate (50 g white bread), or both. Caffeine improved mood and performance. The sensitivity to change of the mood and cognitive measures did not differ in response to the three treatments (all p values > .05). The mood and cognitive measures of mental energy used here have similar sensitivity to detecting change in response to caffeine and carbohydrate.