Functional Limitations, Volunteering, and Diurnal Cortisol Patterns in Older Adults.

Objectives: Older adults often experience functional limitations that affect their everyday lives, but many of them continue to make positive contributions to society and benefit from these contributions themselves. We examine (a) whether older adults' functional limitations are associated with diurnal cortisol patterns and (b) whether these associations vary on volunteering days versus nonvolunteering days.

Methods: Participants were adults aged older than 60 years (N = 435) from the National Study of Daily Experiences, part of the Midlife in the United States Study. They completed an initial interview on functional limitations and background characteristics, indicated volunteering activities in daily interviews, and also provided salivary samples across 4 days.

Results: Multilevel models showed that older adults with greater functional limitations exhibited dysregulated cortisol awakening responses and diurnal cortisol slopes throughout the rest of the day, compared to older adults with lower limitations. Yet, we also observed a significant moderating effect of volunteering on these associations.

Discussion: This study advances our understanding of functional limitations and cortisol stress responses, revealing the benefits of volunteering to older adults who experience these limitations. Rather than treating these older adults solely as care recipients, interventions should offer them opportunities to help others.