Associations between objectively measured sleep characteristics and six-minute walk distance in older adults: the Disparities in Sleep and Cognitive Outcomes (DISCO) study.

STUDY

OBJECTIVES

A decline in physical functioning in older adults has been associated with a higher risk of chronic diseases. Subjective sleep disturbances have been associated with declines in physical functioning with aging. We examined the association between objectively measured sleep characteristics and 6-minute walk distance, a marker of functional capacity, in a sample of older adults.

METHODS

This analysis included 199 participants who were enrolled in the Disparities in Sleep and Cognitive Outcomes (DISCO) study, a longitudinal cohort of older adults aged ≥55 years. Exposures included: sleep duration, sleep percentage, sleep fragmentation, and sleep regularity index measured using 7 days of wrist actigraphy; sleep stages including non-rapid eye movement (REM) stage 3 (N3) and REM, and apnea-hypopnea index (AHI) measured using an overnight type 2 home polysomnography. The primary outcome was the total distance walked in 6 minutes (6MWD). Multiple linear regression was used for analysis.

RESULTS

The mean age of participants was 67.6 (SD = 6.3) years (range 55-84 years), 69.3% were women, 62.3% were white and 84.4% were non-Hispanic. The average 6 MWD was 476.0 (SD = 95.6) meters. In adjusted models (B [95% CI]), higher sleep percentage (2.65 [0.22, 5.08] percent) and greater sleep regularity (1.03 [0.0047, 2.05] units) were associated with higher 6 MWD. Greater sleep fragmentation was associated with lower 6 MWD (-2.56 [-4.02, -1.10] percent). Sleep duration, N3, REM, and AHI were not associated with 6 MWD.

CONCLUSIONS

Poorer objective sleep quality and irregular sleep were associated with poorer functional capacity in older adults. Future work should test whether improving sleep quality and regularity improves physical functioning and overall health in older adults.