Dr. Lennart Levi, director of the Clinical Stress Laboratory at the Karolinska Hospital in Stockholm, has shown, for example, that even quite small changes in the emotional climate or in interpersonal relationships can produce marked changes in body chemistry. Stress is frequently measured by the amount of corticosteroids and catecholamines (adrenalin and noradrenalin, for example) found in the blood and urine. In one series of experiments Levi used films to generate emotions and plotted the resultant chemical changes.