Sleep disturbances with PD patients are common for a variety of reasons. One early symptom of PD is REM sleep behavior sleep disorder (RBD). This typically manifests itself years before the clinical diagnosis of PD based on motor symptoms is made. Sleep disruption, secondary insomnia, restless legs syndrome (RLS), and other sleep issues may be exacerbated by PD medications.
Zesiewicz TA, Sullivan KL, Arnulf I, et al. Practice Parameter: treatment of nonmotor symptoms of Parkinson disease: report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2010;74(11):924-931.