<p>Groups for sleep duration.</p>

Background
The effect of sleep duration on geriatric sarcopenia remains unclear, and evidence of the combined impact of it and BMI on geriatric sarcopenia is scarce.
Aims
To conduct the risk assessment of sleep duration on geriatric sarcopenia and explore its moderating role in the effect of BMI on geriatric sarcopenia based on the CHARLS database.
Methods
Data were extracted from the China Health and Retirement Longitudinal Study (CHARLS) 2011, 2013, and 2015 waves respectively. Logistic regression and Cox regression analyses were conducted to assess the risk of sleep duration for geriatric sarcopenia, and the regulatory effect of sleep duration on the association between BMI and sarcopenia. Subgroup analysis was conducted to enhance the stability of the results.
Results
The four abnormal types of sleep duration were significantly associated with sarcopenia. A significant association between obesity and decreased risk of sarcopenia was observed in sufficient sleep and sleep deprivation groups after the full adjustment of covariates (Adjusted HR = 0.25, 95%CI: 0.10–0.64, P < 0.001; Adjusted HR = 0.13, 95%CI: 0.03–0.53, P = 0.004; Adjusted HR = 0.26, 95%CI: 0.10–0.66, P = 0.005), and relationships of underweight and overweight with sarcopenia were observed in sufficient sleep, sleep deprivation, and mild oversleeping groups. In the group of oversleeping, the associations were not significant.
Conclusion
Abnormal sleep durations including sleep deprivation and oversleeping are linked to a heightened risk of sarcopenia among older adults. Underweight is associated with the increased sarcopenia risk, and overweight is correlated with the decreased risk of sarcopenia, especially in females with abnormal sleep duration except for severe oversleeping, and obesity is associated with the decreased risk of sarcopenia, especially in adults aged over 65 with sleep deprivation.

背景：睡眠时长对老年肌肉减少症（geriatric sarcopenia）的影响尚不明确，且睡眠时长与体质量指数（BMI）联合对老年肌肉减少症的影响证据仍较为匮乏。
研究目的：本研究旨在基于中国健康与养老追踪调查（China Health and Retirement Longitudinal Study, CHARLS）数据库，评估睡眠时长对老年肌肉减少症的风险效应，并探讨睡眠时长在体质量指数对老年肌肉减少症的影响中所发挥的调节作用。
方法：本研究分别提取中国健康与养老追踪调查（CHARLS）2011、2013及2015年追踪队列的数据。采用Logistic回归与Cox回归分析，评估睡眠时长对老年肌肉减少症的风险效应，以及睡眠时长在BMI与肌肉减少症关联中的调节作用。为提升研究结果的稳健性，本研究开展了亚组分析。
结果：四类异常睡眠时长均与肌肉减少症存在显著关联。在充分校正混杂变量后，充足睡眠组与睡眠剥夺组中，肥胖与肌肉减少症风险降低存在显著关联（校正后风险比（HR, Hazard Ratio）=0.25，95%置信区间（CI, Confidence Interval）：0.10~0.64，P<0.001；校正后HR=0.13，95%CI：0.03~0.53，P=0.004；校正后HR=0.26，95%CI：0.10~0.66，P=0.005）；在充足睡眠、睡眠剥夺及轻度睡眠过多组中，体质量过低与体质量过高均与肌肉减少症存在关联。而在睡眠过多组中，上述关联均无统计学意义。
结论：包括睡眠剥夺与睡眠过多在内的异常睡眠时长，与老年人群肌肉减少症风险升高显著相关。体质量过低与肌肉减少症风险升高相关，体质量过高则与肌肉减少症风险降低相关，该关联在除重度睡眠过多外的异常睡眠时长女性群体中尤为显著；肥胖与肌肉减少症风险降低相关，该关联在65岁以上睡眠剥夺人群中尤为显著。