Postoperative sleep disturbance (PSD) is highly prevalent in elderly patients undergoing laparoscopic radical resection of colorectal cancer. Although remimazolam has shown favorable sedative properties and may alleviate perioperative stress, its effects on postoperative sleep architecture remain poorly understood. Polysomnography (PSG), the gold standard for objective sleep assessment, has not been widely used to evaluate these effects in this population. Therefore, this study employs a randomized controlled trial design to verify whether remimazolam is superior to propofol in preserving postoperative sleep quality, thereby offering more evidence-based options for anesthetic management in elderly patients undergoing laparoscopic colorectal cancer surgery.