This chapter presents the clinical history, examination, treatment, management, and the results of the procedures performed on a 27-year-old patient who was admitted for the evaluation of odd sleep-related behaviors. At the time of presentation, the patient had a consistent bedtime of 11.30 pm. Nocturnal polysomnography (PSG) with additional all-night 16-channel EEG running concomitantly with the PSG was obtained. There was no evidence of obstructive sleep apnea (OSA) with normal breathing and normal O2 saturation during sleep averaging 93% with a nadir of 90% and a desaturation index of zero. Given these results, a diagnosis of parasomnia overlap disorder was made. The ICSD-2 defines parasomnia overlap disorder as consisting of both REM-sleep behavior disorder (RBD) and a disorder of arousal. Prognosis is unknown, but careful follow-up is recommended to help with early detection of Parkinsonian disorder or other degenerative neurological disorders that are known to be associated with RBD.