The changes in the synchronization based on wavelet bicoherence are studied in the case of real EEG and ECG signals recorded during nocturnal sleep in patients with obstructive apnea and healthy volunteers. The study involved 72 subjects. The study protocol was approved by the Ethics Committee of the Saratov State Medical University, Ministry of Health of the Russian Federation. The synchronization between the EEG and ECG signals in group of patients with obstructive sleep anoea demonstated a significant increase in the band [0.7; 1.8] Hz against the background of relatively healthy participants. The maximum number of reliable differences between the groups under consideration was recorded in the deep N3 stage of sleep in the EEG channels F3, Fz, C3, P3, Pz, O1, T3. The report was presented at PhysCon 2024 “Features of ECG and EEG Signal Synchronization in Patients with Obstructive Sleep Apnea Syndrome during Nocturnal Sleep”.