Food for thought? Trust your unconscious when energy is low.

Recent studies showed that a period of unconscious thought can help when making complex decisions. Under some circumstances, unconscious thought improves decisions even more than conscious thought. Executive functioning depends on energy provided by glucose, and we know from previous research that the performance of various conscious processes deteriorates when energy is low. Unconscious processes require less energy and may operate unhampered when energy is low. Therefore, we propose that whereas low blood glucose levels impair conscious thought, this is not the same for unconscious thought. An experiment, where we manipulated blood glucose levels, indicated that indeed, when making decisions, the unconscious can best be trusted when blood glucose levels are low, whereas conscious deliberation yields the best results when blood glucose levels are elevated.