To evaluate the extent to which relaxation can buffer the effects of an acute stressor, 80 medical students will undergo the blister wound procedure during each of two GCRC admissions, once at a lower stress baseline, and again 2-3 days before a key exam, and they will be followed daily to assess blister site wound repair after both admissions. Half the subjects will be randomly assigned to receive relaxation training beginning a week prior to the second GCRC admission. The aims of the study are: 1) to assess the linkages among dispositional optimism, expectancies, mood, hormones, and production of proinflammatory cytokines, as well as the extent to which relaxation, age, and gender mediate these relationships; 2) to determine the relationships between hormones and production of proinflammatory cytokines from peripheral blood and at the wound site, and the influence of age, gender, and relaxation on these pathways; 3) to assess relationships between proinflammatory cytokines from peripheral blood and blister chamber fluid and the healing of blister sites; and 4) to determine the extent to which age interacts with optimism and mood to impair cytokine secretion and wound healing.