This study investigates sleep quality in patients with Rotator Cuff Syndrome (RCS) undergoing physical therapy treatment. Existing literature presents a gap regarding longitudinal studies evaluating the impact of physical therapy and different sleeping positions on sleep quality within this specific population. The central hypothesis is that physical therapy, combined with guidance on the best sleeping positions, reduces pain, improves shoulder function, and consequently promotes an improvement in sleep quality for RCS patients over time. The justification for this research lies in the need to better understand the relationship between physical therapy and sleep quality in RCS patients, aiming for the development of more effective and less invasive interventions. Previous studies have demonstrated that chronic pain, a common symptom of RCS, is intrinsically linked to sleep disturbances, which can lead to deleterious effects such as dopamine reduction, alterations in the descending pain modulation system, and central sensitization. Improvements in sleep quality have been observed after surgical procedures such as shoulder arthroscopy and arthroplasty, often associated with improved function and pain reduction. Thus, this study seeks to longitudinally evaluate whether physical therapy is capable of promoting a sustained improvement in sleep quality for patients with RCS

Background and Rationale Rotator Cuff Syndrome (RCS) is a prevalent musculoskeletal condition characterized by pain and functional limitation, which significantly impacts patients' quality of life. While physical therapy is a standard conservative treatment for reducing pain and restoring shoulder function, its longitudinal effect on sleep quality remains under-researched. Chronic pain in RCS is intrinsically linked to sleep disturbances, potentially leading to central sensitization and alterations in the pain modulation system. This study aims to address the gap in literature regarding the added benefit of structured sleep posture guidance when combined with standard rehabilitation.

Study Design and Procedures This is a parallel-group, randomized controlled clinical trial with a 1:1 allocation ratio. The study is designed as a simple-blind trial, where the outcome assessors will be blinded to the participants' group assignments.

Participants will be recruited from a specialized orthopedic and physical therapy center. Following the initial assessment (T0), eligible participants will be randomly assigned to either the Control Group or the Intervention Group using a set of sealed, opaque envelopes generated by an independent researcher.

Intervention Protocols

Control Group (Standard Physical Therapy): Participants will undergo a standardized physical therapy protocol consisting of 10 sessions (twice weekly for 5 weeks). The sessions follow evidence-based clinical practice guidelines for RCS and include:

Education on ergonomics and modifications of activities of daily living. Articular mobilization and manual therapy techniques. Progressive resisted exercises, including both isometric and isotonic modalities, focused on analgesia and functional recovery.

Intervention Group (Physical Therapy + Sleep Posture Guidance): Participants in this group will receive the exact same 10-session physical therapy protocol as the Control Group. Additionally, they will receive structured and personalized sleep posture guidance during the first week, with monthly reinforcements. This additional intervention includes:

Specific instructions on ideal sleeping positions to minimize nocturnal shoulder stress (e.g., avoiding sleeping on the affected shoulder).

Practical guidance on the use of supportive pillows to maintain the shoulder in a neutral and comfortable position throughout the night.

Follow-up and Data Management The total duration of the active treatment phase is 5 weeks. Data collection occurs at three specific time points: baseline (Week 1), post-intervention (Week 5), and a late follow-up (Week 12). Assessments at Week 1 and Week 5 are conducted in person, while the Week 12 follow-up is conducted remotely via an online platform. Data will be stored and managed using secure digital platforms to ensure participant confidentiality and data integrity.

Statistical Plan Overview The sample size of 64 participants was calculated to detect significant changes in sleep quality based on established PSQI score variances from similar populations. Statistical analysis will utilize both descriptive and inferential methods, applying a significance level of p ≤ 0.05 with a 95% confidence interval. Univariate and bivariate analyses will be performed to examine the relationships between pain levels, shoulder function, and sleep quality over time.

Inclusion Criteria:

• Clinical and/or radiological diagnosis of Rotator Cuff Syndrome (RCS).
• Presence of shoulder pain for at least 3 months (chronic pain).
• Patients aged between 18 and 65 years.
• Patients referred for conservative physical therapy treatment.
• Ability to understand and answer the assessment questionnaires (PSQI, MSQ, ASES, and VAS).
• Voluntarily signing the Informed Consent Form (ICF).

Exclusion Criteria:

• History of surgical procedures on the affected shoulder.
• Presence of fractures or recent acute trauma in the shoulder or upper limb.
• Associated neurological disorders, inflammatory systemic diseases (e.g., Rheumatoid Arthritis), or adhesive capsulitis (frozen shoulder).
• Previous diagnosis of primary sleep disorders unrelated to pain (e.g., severe obstructive sleep apnea) already under clinical treatment.
• Recent history of corticosteroid injections in the shoulder (within the last 3 months).