Catathrenia is a rare disorder classified as a respiratory one and characterized by expiratory groans during sleep. We report a case of catathrenia in a 6-year-old male patient, with documented video and audio polysomnography. The diagnosis of catathrenia is made through a detailed analysis of video and audio recordings during the examination. Although there is no association with the risk of physical damage known today, catathrenia presents itself as a source of anxiety among patients and their families. The differentiation of catathrenia with central apnea, obstructive apnea, primary snoring, and parasomnias will influence both the prognosis and the diagnosis and treatment of the patient.