This study aims to analyse the reformulation of medical rehabilitation regulations through the integration of melatonin as a non-narcotic therapy within the Indonesian health law and narcotics law systems to ensure legal certainty, protection of the right to health, and sustainable recovery for narcotics addicts. The research is grounded in the academic problem that, although medical rehabilitation has been recognized under Indonesian narcotics law, there is no explicit regulation governing evidence-based non-narcotic therapies, resulting in legal uncertainty and the continued dominance of a penal approach in rehabilitation practices. This study employs a normative juridical method using statutory, conceptual, and comparative approaches. The novelty of this research lies in identifying the legal gap concerning evidence-based non-narcotic therapies and formulating a regulatory model for integrating melatonin into national rehabilitation standards, an issue that has not been comprehensively examined in previous studies. The findings indicate that the current rehabilitation framework remains characterized by normative inconsistency between health-oriented and penal-oriented approaches. Furthermore, melatonin possesses juridical and medical advantages because it is non-addictive, relatively safe, and consistent with the principles of evidence-based medicine. Therefore, harmonization between narcotics law and health law is necessary through the establishment of national rehabilitation guidelines that explicitly regulate non-narcotic supportive therapies to strengthen legal certainty, protect the right to health, and support sustainable recovery for narcotics addicts. Penelitian ini bertujuan menganalisis pembaruan pengaturan rehabilitasi medis melalui integrasi melatonin sebagai terapi non-narkotika dalam sistem hukum kesehatan dan hukum narkotika Indonesia guna menjamin kepastian hukum, perlindungan hak atas kesehatan, dan pemulihan pecandu narkotika secara berkelanjutan. Penelitian ini berangkat dari permasalahan akademik berupa belum adanya pengaturan yang secara eksplisit mengakomodasi terapi non-narkotika berbasis evidence-based medicine dalam sistem rehabilitasi narkotika nasional, sehingga menimbulkan ketidakpastian hukum dan memperkuat dominasi pendekatan penal dalam praktik rehabilitasi. Penelitian menggunakan metode yuridis normatif dengan pendekatan perundang-undangan, konseptual, dan komparatif. Kebaruan penelitian ini terletak pada identifikasi kekosongan hukum terkait terapi non-narkotika berbasis pembuktian ilmiah serta perumusan model pengaturan integrasi melatonin ke dalam standar rehabilitasi nasional yang belum dikaji secara komprehensif dalam penelitian terdahulu. Hasil penelitian menunjukkan bahwa konstruksi rehabilitasi narkotika masih ditandai oleh ketidakharmonisan antara pendekatan kesehatan dan pendekatan penal. Selain itu, melatonin memiliki keunggulan yuridis dan medis karena bersifat non-adiktif, relatif aman, serta selaras dengan prinsip evidence-based medicine. Oleh karena itu, diperlukan harmonisasi antara hukum narkotika dan hukum kesehatan melalui pembentukan pedoman rehabilitasi nasional yang mengatur terapi pendukung non-narkotika guna memperkuat kepastian hukum dan pemulihan berkelanjutan.