Subjective Age Discrepancy Associates With Sleep Quality in a Large Longitudinal Sample of Middle‐Aged and Older Adults

ABSTRACT

While age is typically measured in chronological terms, subjective age has also been shown to be clinically relevant. Given the clinical importance of subjective age discrepancy (the distinction between chronological and subjective age), we aimed to examine whether it was associated with another important aspect of health, sleep quality, among middle‐aged and older British adults. Data from the English Longitudinal Study of Ageing was analysed. We used a longitudinal approach involving a primary test sample ( N  = 11,050) and an independent replication sample ( N  = 1800). Subjective sleep quality, sleep duration and frequency of difficulties falling asleep, staying asleep or experiencing unrefreshing sleep were self‐reported and subjective age discrepancy was derived from items regarding chronological age and subjective age. Regression analysis was conducted cross‐sectionally within a wave of data collection and longitudinally between two data waves separated by 4 years. Better sleep quality ( β  = −0.11) and longer sleep duration ( β  = −0.03) were associated cross‐sectionally with ‘younger’ subjective age discrepancy and unrefreshing sleep ( β  = −0.12) emerged as the sleep factor most strongly associated with subjective age discrepancy. In the test sample, but not the replication sample, sleep quality had interactions with chronological age, sex and the presence of long‐term illness in its association with subjective age discrepancy. In longitudinal analysis, subjective age discrepancy was a predictor of sleep quality 4 years later, and subjective age discrepancy predicted sleep quality both cross‐sectionally and longitudinally. Sleep quality and subjective age discrepancy emerge as potential sites for intervention to influence each other for enhancement of quality of life in middle‐to‐older aged adults.