BDNF and sleep disorder: We searched the following databases using the following search queries: PubMed (search queries: “neurofilaments,” “sleep disorders and neurofilaments,” “OSA and neurofilaments,” “BDNF and OSA,” “neurodegeneration and OSA,” and “neurodegeneration and neurofilaments”); Google Scholar (search queries: “OSA and neurofilaments,” “sleep disorders and neurofilaments,” “insomnia and neurofilaments,” “neurofilaments and neurodegeneration,” “neurofilaments and OSA and cognition and biomarker,” “OSA and BDNF,” and “neurofilaments and sleep architecture”).