Background: Sleep duration (too short or too long) is associated with lower physical performance. However, the association of sleep duration and physical performance, taking into account the quality of sleep (e.g., sleep disturbance) in older populations, has not been thoroughly investigated.
Methods: Using data from the Chicago Healthy Aging study conducted in 2007-10, we investigated a cross-sectional association of a combination of sleep duration and sleep disturbance with muscle strength (hand grip), and performance [4m gait speed and Short Physical Performance Battery (SPPB)]. The Pittsburgh Sleep Quality Index (PSQI) was used to assess sleep duration [categorized as short (≤ 6 hours), normal (7-8 hours), and long (≥ 9 hours)] and sleep disturbance (defined as either cannot fall asleep within 30 minutes or waking up in the middle of the night or early morning three or more times per week). (See Table and Table Footnote for definitions of sleep duration and disturbance, and physical performance categories). Multivariable logistic regression analysis was used.
Results: The study sample consists of 952 men and 350 women, ages 65-84 (mean age 71) in 2007-10; 9% were African American.12.6 % had SPPB score ≤ 8, 6.8 % had gait speed on 4 meter course < 0.8 m/s, and 23.4 % had low sex-BMI specific handgrip strength. As compared to the group with normal sleep duration (7-8 hours) without sleep disturbance, adjusted odds (95% confidence interval) of low gait speed <0.8 m/s in those with short sleep duration (≤ 6 hours) and sleep disturbance was much higher [2.00 (1.06-3.75)]. Similarly, the odds of low sex-BMI specific handgrip strength was about 2 times higher in those with long duration of sleep (≥ 9 hours), compared to those with normal sleep duration without sleep disturbance. No association was found for Short Physical Performance Battery (see Table).
Conclusion: In older age, short sleep duration with poor quality as well as excessive sleep duration were associated with the greater likelihood of having low muscle strength and performance.