Sleep quality is a key physiological factor influencing immune function, inflammatory response, and pain perception. This prospective observational study aims to evaluate whether preoperative sleep quality predicts postoperative inflammation, pain severity, and analgesic consumption in patients undergoing elective breast cancer surgery.

Preoperative sleep quality will be assessed using the Pittsburgh Sleep Quality Index (PSQI). Systemic inflammatory response will be evaluated using the Systemic Immune-Inflammation Index (SII), calculated from routine hematological parameters. Postoperative pain will be assessed using the Visual Analog Scale (VAS), and analgesic consumption will be recorded within the first 24 hours.

The study aims to determine whether poor sleep quality is associated with increased inflammatory response, higher pain scores, and greater analgesic requirement.

Sleep plays a crucial role in regulating immune responses, inflammatory pathways, and pain modulation. Sleep disturbances have been associated with increased pro-inflammatory cytokine activity and altered pain perception.

Surgical procedures represent a significant physiological stressor that triggers inflammatory responses and postoperative pain. Identifying modifiable preoperative factors that influence these outcomes is of clinical importance.

This prospective observational study will be conducted in patients undergoing elective breast cancer surgery. Preoperative sleep quality will be assessed using the Pittsburgh Sleep Quality Index (PSQI). Inflammatory response will be evaluated using the Systemic Immune-Inflammation Index (SII), calculated from neutrophil, lymphocyte, and platelet counts.

Postoperative pain intensity will be assessed using the Visual Analog Scale (VAS), and total analgesic consumption within the first 24 hours will be recorded.

The study aims to determine whether preoperative sleep quality is an independent predictor of postoperative inflammatory response, pain severity, and analgesic requirement.

Inclusion Criteria:

• Female patients aged 18 to 70 years
• Scheduled for elective breast cancer surgery
• American Society of Anesthesiologists (ASA) physical status I to III
• Able to understand and complete the Pittsburgh Sleep Quality Index (PSQI)
• Willing to participate in the study
• Provided written informed consent

Exclusion Criteria:

• Active infection
• History of chronic inflammatory disease or autoimmune disease
• Use of steroids or immunosuppressive drugs within the past 6 months
• Known diagnosis of obstructive sleep apnea syndrome
• Severe cognitive impairment preventing completion of the questionnaire
• Planned emergency surgery
• Refusal to participate or failure to provide informed consent

The study population will include female patients aged 18-70 years undergoing elective breast cancer surgery at a tertiary oncology center. Eligible procedures include breast-conserving surgery, lumpectomy, and mastectomy with or without axillary dissection. Preoperative sleep quality will be assessed using the Pittsburgh Sleep Quality Index (PSQI). All patients will receive standard perioperative care without any intervention. This observational cohort represents real-world clinical practice and allows evaluation of the association between preoperative sleep quality and postoperative outcomes.

Individual participant data (IPD) will not be shared. The study involves sensitive clinical data collected from patients in a single-center setting, and data sharing is restricted in order to protect patient confidentiality and comply with institutional and ethical regulations.

De-identified and aggregated data may be available from the corresponding author upon reasonable request, subject to approval by the institutional ethics committee.