NEFL and Cognitive impairment: Greater sleep maintenance insomnia was associated with greater cognitive deficits (Trail A P ≤ 0.001, R2 = 0.78; SDMT P = 0.008, R2 = 0.63; Trail B P = 0.013, R2 = 0.60) and higher levels of neurofilament light (P = 0.015, R2 = 0.39).