This chapter discusses the case of a 27-year-old male who was admitted to the hospital with right arm numbness. It presents the clinical history, examination, follow-up, treatment, diagnosis, and the results of the procedures performed on the patient. His vital signs were normal. There was mild expiratory wheezing at the bases bilaterally related to an upper respiratory infection. There was reduced sensation to light touch, pinprick and vibration in the right upper extremity in C6-C7 distribution. MRI of the brain showed multiple small hyperintense lesions in white matter throughout both cerebral hemispheres and the brainstem. An overnight sleep study followed by a multiple sleep latency test (MSLT) revealed REM sleep without atonia and abundant myoclonic jerks in REM sleep. A diagnosis was made of probable parasomnia overlap disorder in the context of multiple sclerosis. Parasomnia overlap disorder responds favorably to the administration of clonazepam.