Patient description: A 57-year old farmer was diagnosed with Parkinson's disease a year ago. He experiences slowness of movement and tremors. His past medical history is significant for hypertension and hypercholesterolemia. He lives with his wife. They have three children. He used to be active with planting and taking care of their farm animals before his diagnosis. The patient complains of shaking and slow movement. He had difficulty entering through a door, as he was frozen and needed guidance to step in. His handwriting is getting smaller. He is on Levodopa and Trihexyphenidyl. He stated his medications help with shaking and slow movement. But he still has difficulty initiating movements, stiffness and slowness in general. He is an alert and cooperative man who doesn't have any signs of dementia. He doesn't smoke or use any illicit drugs.

Clinical trial eligibility criteria: eligible ages (years): 30.0-75.0,  REM Sleep Behavior Disorder Pre-motor Parkinson Disease Symptomatic Parkinson Disease Male or female of age between 30 and 75 years at time of enrollment. Diagnosis of idiopathic REM sleep behavior disorder (iRBD) or Diagnosis of hyposmia. Diagnosis of RBD will be, established either as 'definite RBD' according to the proposed by the International Classification of Sleep Disorders (ICSD)-2 [AASM, 2005] or 'probable RBD' following a score of 6 or higher in the RBD questionnaire (RBDSQ) with a score of at least 1 in subitems 6.1 to 6.4 of question 6. At least one of the following: 1. Diagnosis of hyposmia. Diagnosis of hyposmia will be established as a University of Pennsylvania Smell Identification Test (UPSIT) score < 20th percentile for the individual's age group and sex. 2. Functional constipation, assessed by a scores > 4 on a questionnaire based on modified ROME III diagnostic criteria. 3. Color vision abnormality, as assessed using HRR Pseudoisochromatic Plates, in the absence of congenital dyschromatopsia. 4. Symptoms of depression, as assessed by a Beck Depression Inventory (BDI) fast screen score >3 or concurrent use of antidepressant medications Abnormal 123I-MIBG myocardial scintigraphy, as defined by a Late H/M ratio < 2.2 and/or a WR >30%, with normal cardiac ejection fraction (LVEF >55%) Capacity to give informed consent  Secondary Parkinsonism, including tardive Concurrent dementia defined by a score lower than 22 on the MoCA Concurrent severe depression defined by a BDI fast screen score greater than 13 Comorbidities related to SNS hyperactivity Heart failure (LVEF <45%) Recent myocardial revascularization (<12 weeks) Chronic Hypertension (SBP>140mmHg-DBP>90mmHg) Atrial fibrillation Diabetes mellitus COPD Sleep Apnea Severely reduced kidney function (Glomerular Filtration Rate<30ml/min) Contraindications to the use of carvedilol Asthma or bronchospasm Recent myocardial infarction (<48 h) Ongoing unstable angina Cardiogenic shock or prolonged hypotension Second or Third-Degree AV block Significant valvular aortic stenosis Obstructive cardiomyopathy, or constrictive pericarditis Symptomatic Bradycardia (HR<60) or Sick Sinus Syndrome Stroke within the past 1 month Severe Hepatic Dysfunction Allergy/hypersensitivity to iodine or study medication