Objectively measured sleep and physical function: Associations in low-income older adults with disabilities

Late-life sleep health has been tied to physical function, but little is known about these associations among socially disadvantaged populations.

We determined cross-sectional associations of sleep with physical function in low-income, predominantly Black older adults with disabilities.

One hundred thirty-six older adults (mean age 76.0 years, 83.8% women, 82.4% Black).

Primary predictors were actigraphic total sleep time (TST), wake after sleep onset (WASO), and subjective sleep complaints. Outcomes were objective physical performance (Short Physical Performance Battery (SPPB)) and participant-reported difficulties in basic and instrumental activities of daily living (ADLs and IADLs).

In regression models adjusted for potential confounders, both longer TST and greater WASO were associated with lower SPPB scores and increased IADL difficulty. Participants with a mean TST in the longest (>7.5 hours) vs. intermediate (6.3-7.5 hours) tertile had 27% higher odds of additional IADL difficulty (incident rate ratio = 1.27, 95% confidence interval [CI] 1.03, 1.58). Each additional 10 minutes of WASO was associated with 0.13 point lower SPPB scores (B = -0.13, 95% CI -0.25, -0.01) and increased IADL difficulty (B = 0.02, 95% CI 0.0003, 0.04). Sex moderated the associations of WASO with IADL and ADL difficulties: associations were stronger for males. Subjective sleep complaints were not statistically significantly associated with function.

Among disabled, low-income, mostly Black older adults, objective measures of long sleep and greater WASO are associated with poorer physical function. Effect sizes for the associations were modest; however, findings may have important implications given the significant consequences of decreased function on quality of life and caregiving demands.