Interindividual Differences and Intraindividual Variability in the Cortisol Awakening Response

This article shows age and gender differences in the magnitude and day-to-day variability of the cortisol awakening response (CAR) using a national sample of 1,143 adults who completed the second wave of the National Study of Daily Experiences, a part of the Midlife Development in the United States survey. Participants between the ages of 33 and 84 years completed 8 consecutive nightly interviews and provided 4 saliva samples (upon waking, 30 min after waking, before lunch, and before bed) on 4 consecutive interview days. Results revealed substantial day-to-day variability in the CAR as well as significant Age × Gender interactions, indicating that although no systematic age-related differences emerged for women, the magnitude and day-to-day variability of the CAR increased with age among men.