Association Between Preoperative Sleep Disturbance and Postoperative Delirium in Adults Undergoing Elective Surgery

Background Postoperative delirium (POD) is a frequent and severe neuropsychiatric complication in surgical patients, often leading to prolonged hospitalization, cognitive decline, and increased healthcare costs. Emerging evidence suggests that preoperative sleep disturbances may significantly contribute to POD risk. This study investigates the association between preoperative sleep quality and POD among adults undergoing elective surgery. Methods A prospective cohort study was undertaken in Islamabad, Pakistan, between December 8, 2024, and March 18, 2025, among 300 patients aged 40 years and older undergoing elective surgery. Pittsburgh Sleep Quality Index (PSQI) was administered preoperatively, whereas POD and cognitive functioning were measured by the Confusion Assessment Method (CAM) and the Mini-Mental State Examination (MMSE), respectively. Statistical analysis involved Pearson correlations, independent t-tests, ANOVA, chi-square tests, and multiple regression, which was conducted using SPSS version 26.0 (IBM SPSS Statistics for Windows, IBM Corp., Armonk, NY). Results Poor quality of sleep in the preoperative period correlated significantly with more delirium symptoms (r = 0.374, p < 0.001) and lower cognitive function (r = 0.589, p < 0.001). Those with existing cognitive dysfunction demonstrated poorer sleep patterns and MMSE scores. The only notable exceptions here were for both extremely short (two to four hours) and excessively long (eight to 10 hours) sleep durations, which were each accompanied by increased confusion symptoms. Regression analysis showed that PSQI and MMSE scores significantly predicted CAM results (p < 0.05). Moreover, chronic illnesses like respiratory diseases and cognitive conditions were associated with disturbed sleep and decreased perceived restfulness. Conclusion Preoperative sleep disturbances are strongly related to a high risk of POD and reduced cognitive function in adults with elective surgery. Systematic preoperative screening for sleep quality and the use of targeted sleep interventions could provide effective strategies for POD incidence reduction and optimization of postoperative outcomes. Longitudinal studies are advised in the future to confirm these findings and inform improvements in perioperative care.