This combination of reactions to stress is also known as the "fight-or-flight" response because it evolved as a survival mechanism, enabling ...SkiptocontentUnderstandingthestressresponseChronicactivationofthissurvivalmechanismimpairshealthUpdated:July6,2020Published:March,2011Astressfulsituation—whethersomethingenvironmental,suchasaloomingworkdeadline,orpsychological,suchaspersistentworryaboutlosingajob—cantriggeracascadeofstresshormonesthatproducewell-orchestratedphysiologicalchanges.Astressfulincidentcanmaketheheartpoundandbreathingquicken.Musclestenseandbeadsofsweatappear.Thiscombinationofreactionstostressisalsoknownasthe"fight-or-flight"responsebecauseitevolvedasasurvivalmechanism,enablingpeopleandothermammalstoreactquicklytolife-threateningsituations.Thecarefullyorchestratedyetnear-instantaneoussequenceofhormonalchangesandphysiologicalresponseshelpssomeonetofightthethreatofforfleetosafety.Unfortunately,thebodycanalsooverreacttostressorsthatarenotlife-threatening,suchastrafficjams,workpressure,andfamilydifficulties.Overtheyears,researchershavelearnednotonlyhowandwhythesereactionsoccur,buthavealsogainedinsightintothelong-termeffectschronicstresshasonphysicalandpsychologicalhealth.Overtime,repeatedactivationofthestressresponsetakesatollonthebody.Researchsuggeststhatchronicstresscontributestohighbloodpressure,promotestheformationofartery-cloggingdeposits,andcausesbrainchangesthatmaycontributetoanxiety,depression,andaddiction..Morepreliminaryresearchsuggeststhatchronicstressmayalsocontributetoobesity,boththroughdirectmechanisms(causingpeopletoeatmore)orindirectly(decreasingsleepandexercise).SoundingthealarmThestressresponsebeginsinthebrain(seeillustration).Whensomeoneconfrontsanoncomingcarorotherdanger,theeyesorears(orboth)sendtheinformationtotheamygdala,anareaofthebrainthatcontributestoemotionalprocessing.Theamygdalainterpretstheimagesandsounds.Whenitperceivesdanger,itinstantlysendsadistresssignaltothehypothalamus.CommandcenterWhensomeoneexperiencesastressfulevent