Momentary subjective age is associated with perceived and physiological stress in the daily lives of old and very old adults.

= 85.92 years) who reported their momentary subjective age and perceived stress and also provided saliva samples up to seven times a day over seven consecutive days. Dynamic structural equation models showed that both higher momentary perceived stress and higher cortisol levels preceding the measurement predicted an older momentary subjective age. In contrast, subjective age at the previous measurement did not predict subsequent stress. These effects were moderated by participant age group and grip strength, albeit not consistently. Our results corroborate and extend earlier findings that both self-reported and physiological stress are important explanatory variables for people's subjective age variation even on relatively short time scales and shed light on differential time-ordered dynamics between stress and subjective age in daily life. Findings also inform theoretical models of subjective age that highlight the importance of contextual, momentary influences on how old people feel and help better understand how biological and psychological processes are intertwined in later life. (PsycInfo Database Record (c) 2022 APA, all rights reserved).