Controversy surrounds the pathogenesis of neurocognitive daytime dysfunction exhibited by patients with obstructive sleep apnea syndrome (OSAS). Underlying brain dysfunctions and damage have long been suspected as a cause of some of this impairment. Neuroimaging has enabled scientists to test these long-held theories. This paper is based on a comprehensive review of recent publications on neuroimaging studies in this area. It seeks to highlight results of recent research, which suggest connections between persistent neurocognitive daytime impairment of executive functions, underlying signs of cerebral metabolic impairment and neurodegeneration, considering possible cerebrovascular impairment in OSAS patients. We propose the existence of a neurodegenerative process.