The impact of increasing blood glucose on psychological functioning.

In the first experiment, after taking a drink containing either glucose or a placebo, subjects performed a task that involved watching a screen for 25 min, during which they had to press a space bar when one of four digits appeared. Over the duration of the task the performance of both groups improved, but in those taking the glucose drink the improvement occurred significantly earlier. In a second experiment subjects for 20 min performed a task requiring hand-eye coordination. The taking of a glucose-containing drink was not associated with a change in performance. A review of the relevant literature suggested that glucose is beneficial when performing tasks demanding little mental capacity.