Hans Selye (1976) divided his stress syndrome into three stages and, in doing so, pointed out the seriousness of prolonged stress on the body and the need for identification and intervention.

1. Alarm stage - This is the immediate physiological (fight or flight) response to a threat or perceived threat.
2. Resistance - If the stress continues, the body adapts to the levels of stress and attempts to return to homeostasis.
3. Exhaustion - With prolonged exposure and adaptation, the body eventually becomes depleted. There are no more reserves to draw upon, and serious illness may now develop (e.g., hypertension, mental disorders, cancer). Selye teaches us that without intervention, even death is a possibility at this stage.

CLINICAL PEARL: Identification and treatment of chronic, posttraumatic stress disorder (PTSD) and unresolved grief, including multiple (compounding) losses, are critical in an attempt to prevent serious illness and improve quality of life. (See PTSD table and PTSD Treatments in Disorders/Interventions tab and Military, Families, and PTSD in Crisis tab.)