In most people, the substance increases self-confidence, concentration, and willingness to take risks while at the same time reducing sensitivity to pain, hunger, thirst, and the need for sleep. In September 1939, Ranke tested the drug on 90 university students and concluded that Pervitin could help the Wehrmacht win the war. Cocaine, whose effects substantially overlap with those of amphetamine but feature greater euphoria, was later added to the formulation to increase potency through the multiplicative effects of drug interaction and to reinforce use by individuals.