NEFL and Parkinson disease: Furthermore, specific RBD behaviors, such as aggressive or action-packed dreams (β = 0.009; P = 0.028) (Fig. 5B), hurting bed partner (β = 0.011; P = 0.033) (Fig. 5C), speaking in sleep (β = 0.010; P = 0.012) (Fig. 5D), sudden limb movements (β = 0.009; P = 0.016) (Fig. 5E), and complex movements (β = 0.016; P = 0.014) (Fig. 4F) were observably correlated with a longitudinal increase in serum NfL levels among PD patients.