Encyclopedia of Psychology | Stress

The physiological and psychological responses to situations or events that disturb the equilibrium of an organism.

While there is little consensus among psychologists about the exact definition of stress, it is agreed that stress results when demands placed on an organism cause unusual physical, psychological, or emotional responses. In humans, stress originates from a multitude of sources and causes a wide variety of responses, both positive and negative. Despite its negative connotation, many experts believe some level of stress is essential for well-being and mental health.

Stressors—events or situations that cause stress— can range from everyday hassles such as traffic jams to chronic sources such as the threat of nuclear war or over-population. Much research has studied how people respond to the stresses of...