Mental stress during daily life, including reported feelings of tension, frustration, and sadness, can more than double the risk of myocardial ischemia in the subsequent hour. The unadjusted relative risk of occurrence of myocardial ischemia in the hour following high levels of negative emotions was 3.0) for tension,2.9 for sadness, and 2.6 for frustration. The corresponding risk ratios adjusted for physical activity and time of day were 2.0 for tension, 2.0 for sadness, and 2.2 for frustration. JAMA. 1977; 277:1521-1526.