The type A personality is a collection of behaviors that include impatience and a sense of urgency about accomplishing most tasks; aggressiveness and sometimes hostility toward others, especially those who “get in the way”; and a desire for achievement that leads to exaggerated competitiveness and striving for success. Type A personalities lead fast-paced lives; they speak quickly, walk quickly, eat quickly—all in an attempt to accomplish as much as possible in as little time as possible. By comparison, type B personalities are relaxed and easygoing, less concerned with the pressures of success (but are not lazy), and generally lead less hectic lives.

Interest in type A behavior first arose in the 1950s when two cardiologists, Meyer Friedman and Ray Rosenman, noticed that patients with ...