Changes in functional connectivity during sleep in patients with hypertension and obstructive sleep apnea

Anna Orlova; Natalya Akimova; Larisa Konshina; Maxim Zhuravlev; Anastasiya Runnova; Anton Kiselev

doi:10.1140/epjs/s11734-025-02102-z

2024 Impact factor 2.3

Special Topics

Eur. Phys. J. Spec. Top.
https://doi.org/10.1140/epjs/s11734-025-02102-z

Regular Article

Changes in functional connectivity during sleep in patients with hypertension and obstructive sleep apnea

Anna Orlova¹, Natalya Akimova², Larisa Konshina², Maxim Zhuravlev¹^,2^,3^a, Anastasiya Runnova¹^,2^,3 and Anton Kiselev¹

¹ Center for Coordination of Fundamental Scientific Activities, National Medical Research Center for Therapy and Preventive Medicine, Petroverigsky Lane, 10, 101000, Moscow, Russian Federation
² Institute of Biodigital Health Systems, Saratov State Medical University named after V.I. Razumovsky, Bolshaya Kazachya St., 112, 410012, Saratov, Russian Federation
³ Institute of Physics, Saratov State University named after N.G. Chernyshevsky, Astrakhanskaya St., 83, 410012, Saratov, Russian Federation

^a This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 15 October 2025
Accepted: 8 December 2025
Published online: 16 December 2025

Abstract

This study compared phase synchronization across ten frequency bands ( $Δ f_{1} [0.2 ; 0.8]$ $\Delta f_1 [0.2;0.8]$ to $Δ f_{10} [10 ; 12]$ $\Delta f_{10} [10;12]$ Hz) using wavelet bicoherence (WB) analysis of polysomnographic recordings from 643 participants. The study cohort included healthy controls ( $n = 103$ $$n=103$$ ) and patients with stage I ( $n = 130$ $$n=130$$ ), II ( $n = 260$ $$n=260$$ ), and III ( $n = 150$ $$n=150$$ ) hypertension. A subset of participants had comorbid obstructive sleep apnea (OSA). Increasing severity of both OSA and hypertension was associated with elevated functional connectivity between heart rate (HR) and oxygen saturation ( ${SaO}_{2}$ $\textrm{SaO}_2$ ) in the $Δ f_{1}$ $\Delta f_1$ – $Δ f_{4}$ $\Delta f_4$ bands and its decrease in the $Δ f_{5}$ $\Delta f_5$ – $Δ f_{10}$ $\Delta f_{10}$ bands. Significant differences ( $p < 0.01$ $$p<0.01$$ ) in interhemispheric EEG connectivity were observed in the control group across $Δ f_{1}$ $\Delta f_1$ – $Δ f_{9}$ $\Delta f_9$ and in stage III hypertension patients across $Δ f_{2}$ $\Delta f_2$ – $Δ f_{4}$ $\Delta f_4$ , when stratified by OSA status ( $AHI \geq 15$ $\textrm{AHI}\ge 15$ vs. $AHI < 15$ $\textrm{AHI}< 15$ events/h). Connectivity analysis of ${SaO}_{2}$ $\textrm{SaO}_2$ - HR recordings revealed significant apnea-related differences in: (1) healthy controls ( $Δ f_{1}$ $\Delta f_1$ : $p \approx 0.0037$ $p\approx 0.0037$ ; $Δ f_{2}$ $\Delta f_2$ : $p \approx 0.0048$ $p\approx 0.0048$ ; $Δ f_{3}$ $\Delta f_3$ : $p \approx 0.0003$ $p\approx 0.0003$ ; $Δ f_{4}$ $\Delta f_4$ : $p \approx 0.0002$ $p\approx 0.0002$ ) and (2) stage II hypertension group ( $Δ f_{9}$ $\Delta f_9$ : $p \approx 0.0081$ $p\approx 0.0081$ ). Notably, normotensive participants with $AHI \geq 15$ $\textrm{AHI}\ge 15$ events/h showed significantly higher WB connectivity in the $Δ f_{1}$ $\Delta f_1$ band compared to multiple hypertensive groups. In the $Δ f_{4}$ $\Delta f_4$ band, controls with $AHI \geq 15$ $\textrm{AHI}\ge 15$ events/h also exhibited higher connectivity than several hypertensive subgroups. Across the $Δ f_{2}$ $\Delta f_2$ – $Δ f_{9}$ $\Delta f_9$ bands, all hypertension groups showed significant WB connectivity differences ( $p < 0.005$ $$p < 0.005$$ ) between OSA subgroups. The simultaneous assessment of apnea severity and hypertension stage effectively captures altered brain–heart interaction, suggesting potential biomarkers for evaluating hypertension severity and predicting disease progression.

Copyright comment Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Anna Orlova, Natalya Akimova, Larisa Konshina, Maxim Zhuravlev, Anastasiya Runnova and Anton Kiselev contributed equally to this work.

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

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Changes in functional connectivity during sleep in patients with hypertension and obstructive sleep apnea

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