Objectives <p>CDK4/6 inhibitors have significantly improved progression-free survival in hormone receptor-positive (HR+)/HER2-negative advanced breast cancer. However, their psychological impact, particularly on sleep quality, anxiety, and menopausal symptoms, remains underexplored.</p> Objectives <p>This study aimed to evaluate the prevalence of insomnia and its associations with psychological and menopausal symptoms in patients receiving CDK4/6 inhibitor therapy, using validated patient-reported outcome measures.</p> Methods <p>A total of 63 women with stage IV HR+/HER2– breast cancer treated with either palbociclib or ribociclib were included. Sleep disturbances were assessed using the Pittsburgh Sleep Quality Index (PSQI), anxiety and depression via the Hospital Anxiety and Depression Scale (HADS), menopausal symptoms with the Menopause Rating Scale (MRS), and health-related quality of life using the Nottingham Health Profile (NHP).</p> Results <p>nsomnia (PSQI &gt;5) was present in 54% of patients. Insomnia was significantly associated with younger age and presence of young children. While 41.2% and 39.7% of patients showed borderline or abnormal scores on HADS-A and HADS-D, respectively, no significant correlations were found between HADS scores and insomnia. Patients with insomnia had significantly higher MRS scores, indicating greater menopausal symptom burden. NHP analysis revealed no significant difference in total scores; however, domain-specific impairment in sleep was observed among patients with insomnia.</p> Conclusion <p>Sleep disturbances are prevalent among HR+/HER2– advanced breast cancer patients receiving CDK4/6 inhibitors, often coexisting with menopausal symptoms and psychological distress. These findings highlight the need for routine screening and comprehensive supportive care strategies targeting sleep and mental health to optimize quality of life in this population.</p>