U-shaped association between sleep duration and subjective cognitive complaints in Chinese elderly: a cross-sectional study. - Lin, Li-Hua; Xu, Wen-Qi; Wang, Shi-Bin; Hu, Qing; Zhang, Ping; Huang, Jia-Hao; Ke, Yun-Fei; Ding, Kai-Rong; Hou, Cai-Lan; Jia, Fu-Jun (BMC Psychiatry, 2022)