Interestingly, the pathologically alpha-synuclein affected brain regions in PD patients with sleep disorders have been shown in some studies to be consistent with the ascending arousal system monoaminergic pathways, including the noradrenergic locus coeruleus, serotoninergic raphe nuclei, dopaminergic periaqueductal gray matter, and histaminergic tuberomamillary nucleus [32]. This evidence concerns the gene SNCA and sleep disorder.