Association Between Sleep Duration and Mid-Thigh Muscle Composition

Abstract

Age-related changes in sleep are broadly documented and complaints of sleep difficulties are more common among older adults. Although sleep disorders are viewed as a health threat in several physiological systems, it is unclear how thigh lean mass and muscle attenuation, markers of sarcopenia, are affected by sleep. PURPOSE: This study aimed to examine the association between 24-hour sleep duration and mid-thigh muscle composition. METHODS: 2,438 men and 3,326 women aged 66 to 96 years, residents in the Reykjavik area (Iceland), were included in this cross-sectional study. Mid-thigh muscle area (cm2) and muscle attenuation (Hounsfield units, HU) were assessed with a four-row detector computed tomography system. The muscle attenuation was used as an indicator of muscle fat infiltration; lower HU indicates greater fat infiltration. Sleep and nap habits were assessed using a questionnaire. Total 24-hour sleep duration was estimated as the sum of nighttime sleep hours and daytime nap hours. Statistical analysis was performed using multivariable linear regression. RESULTS: We found that after adjustment for age and body mass index (BMI) long sleep duration (>8 h/day) was negatively associated with thigh lean area in both men (B= −2.2, 95% confidence interval (CI) = −4.0, −0.4) and women (B=−2.9, 95% CI = −3.8, −1.0) and with muscle attenuation (B=−1.0, 95% CI = −1.5, −0.4) only in women. After adjustments for all relevant covariates (including age, BMI, health and lifestyle factors) the association between long sleep duration and thigh lean area was attenuated and became non-significant. In women, the associations between long sleep duration and muscle attenuation were significant in both the age and BMI- and the full-adjusted model. In men these associations were not significant. No associations were observed for short sleep duration (<6 h/day) and both muscle parameters. CONCLUSIONS: Long sleep duration, particularly in old women, is associated with thigh muscle attenuation. Whether optimization of sleep can ameliorate age-associated intramuscular adipose tissue warrants further studies. Supported by Intramural Research Program of the NIH, NIA; the AGES-Reykjavik Study is funded by NIH Grant N01-AG-12100, the NIA Intramural Research Program, Hjartavernd, and the Althingi.