The molecular mechanisms that disrupt circadian regulation in PD are not clear, however patients with α-synucleinopathies exhibit DNA methylation changes associated with clock genes, for example decreased methylation of the NPAS2 gene promoter from PD patients (63) and of PER1 and CRY1 from DLB patients (64) leukocytes have been reported. Here, PER1 is linked to Parkinson disease.