Interaction effects of sleep duration and activities of daily living on depressive symptoms among Chinese middle-aged and older adult individuals: evidence from the CHARLS - Wang, Tianmeng; Han, Wenjin; Wang, Caihua; Kang, Yanqing; Wang, Yaping; Lei, Shuangyan; Hui, Zhaozhao; Li, Ning; Wang, Xiaoqin (Frontiers in Public Health, 2025)