Correlation Between Blue Light Exposure from Digital Device Screens and Sleep Quality Among Students in the Faculty of Medicine, Universitas Sumatera Utara Class of 2019. Sumat. Med. J. [Internet]. 2023 May 15 [cited 2026 Feb. 4];6(2):71-6. Available from: https://idjpcr.usu.ac.id/smj/article/view/11051