Effects of esketamine on postoperative pain, anxiety, depression, sleep, and inflammation in pregnancies undergoing cesarean section: A randomized controlled trial - Yijun Wang; Xiaolu Lin; Xiang Zou; Renqin Zhang; Juanxia Xing; Li Zhang; Jie Shen; Xiaoliang Zhang; Daju Zhou; Junhua Zhang (PLoS ONE, 2026)