Objectives: To determine whether intrathecal morphine (ITM) analgesia in abdominal surgery for presumed gynecological malignancy was associated with better self-reported sleep quality postoperatively compared with epidural analgesia (EDA), and to evaluate risk factors for bad sleep quality. Methods: A secondary analysis of a randomized open controlled trial, comparing ITM and EDA as postoperative analgesia in 80 women undergoing laparotomy under general anaesthesia in an enhanced recovery after surgery framework. A total of 38 women allocated to ITM and 39 to EDA completed the study. The Swedish Postoperative Symptoms Questionnaire assessed symptoms and sleep quality during the first postoperative week. Multiple logistic regression models evaluated risk factors. The results are presented as adjusted odds ratios with 95% CIs. Results: The sleep quality night-by-night did not differ significantly between the women who had ITM or EDA. Risk factors for bad sleep quality for night 1 were age (0.91; 0.84–0.99), operation time (1.02; 1.00–1.03), and opioid consumption (0.96; 0.91–0.99). For night 2, regular use of hypnotics preoperatively (15.81; 1.52–164.27) and opioid consumption (1.07; 1.00–1.14) were independent risk factors for bad sleep. After the second night, no risk factors were disclosed. Conclusions: ITM and EDA did not appear to affect the sleep quality postoperatively differently in women undergoing laparotomy for presumed gynecological malignancy. Risk factors for self-reported bad sleep quality varied during the first 3 days after surgery. Younger age, longer operation time, and preoperative use of hypnotics were associated with bad sleep quality, whereas the effect of opioid consumption on sleep quality varied depending on the time since surgery. These findings merit further studies. © 2023 The Society of Obstetricians and Gynaecologists of Canada/La Société des obstétriciens et gynécologues du Canada