A term coined by Dr. Margaret Blaustein and Kristine Kinniburgh that refers to the range of intensity of emotions and physiological arousal that a person typically seeks to inhabit. Complex trauma can constrict a person’s capacity to feel their feelings– and adjust their intensity as needed– without becoming overwhelmed and dysregulated. Some people survive by limiting their behaviors, relationships and life choices in order to remain inside their comfort zone. Some resort to desperate measures to return to it when triggered. Some exist by living primarily within very high or low ranges of internal experience. Helping clients to identify and expand their comfort zone is an important clinical objective of the ARC intervention model. This construct shares some features with the earlier concept of window of tolerance.