Melatonin for sleep disturbance in breast cancer patients

Many women with breast cancer who are taking hormone-blocking therapy (such as tamoxifen or aromatase inhibitors) experience significant sleep problems. Poor sleep affects quality of life, mood, and overall health, yet there are few well-studied treatments specifically for this group. This trial is testing whether melatonin — a natural hormone the body makes to regulate sleep — can help improve sleep in women receiving hormone-blocking treatment for breast cancer. Participants will be randomly and blindly assigned to take either melatonin tablets or a placebo (dummy tablets) every evening before bed for 12 weeks. Neither the participant nor the research team will know which they are taking until the study is complete. Sleep will be monitored using questionnaires and a wrist-worn activity tracker (actigraph watch), and participants will keep a medication diary. You may be eligible if you are female, 18 or older, have stage 1 to 3 breast cancer, have been on hormone-blocking therapy for at least 3 months, and have poor sleep that started or worsened after your breast cancer diagnosis. Women with sleep apnoea, those currently using sleeping medications, or those working regular night shifts are not eligible. This trial offers a simple, non-invasive way to potentially address one of the most common and distressing side effects of breast cancer treatment.