Adaptation of recurrence plot method to study a polysomnography: changes in EEG activity in obstructive sleep apnea syndrome

The aim of this work is to numerically evaluate the characteristics of the stages of nocturnal sleep, recorded in patients with respiratory disorders compared with a group of healthy participants in clinical trials. Based on the use of recurrent analysis, it was shown that the recurrence parameters of the two nocturnal sleep recordings, both for patients with severe obstructive sleep apnea syndrome and for healthy participants, do not show statistical differences. At the same time, comparison of the recurrent characteristics of the stages of nocturnal sleep in the two groups demonstrate statistical differences that are promising for further analysis. During the deepest stages of NREM sleep (N3 and N4), the R characteristics of healthy participants are reduced and significantly homogeneous against the background of heterogeneous results of the group of OSA patients. The opposite situation is observed for stage N2, at which the dynamics of RA characteristics in OSA patients becomes monotonous, repeating from participant to participant. The maximum differences for apparently healthy participants and OSA patients were observed during the REM sleep stage, when the < R R stage > value increased significantly in the presence of respiratory disorders.