https://doi.org/10.1140/epjs/s11734-025-02116-7
Regular Article
Impact of 6 months of pap treatment on sleep spindle activity in obstructive sleep apnea: a pilot study
1
Scientific Centre for Family Health and Human Reproduction Problems, 16, Timiryazev Str., 664003, Irkutsk, Russia
2
Department of Biology, Saratov State University, Astrakhanskaya 82, 410012, Saratov, Russia
3
Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, Prospekt Entuziastov 13, 410049, Saratov, Russia
a
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Received:
10
November
2025
Accepted:
15
December
2025
Published online:
4
February
2026
Abstract
Although changes in sleep macrostructure in obstructive sleep apnea (OSA) and their improvement with positive airway pressure (PAP) treatment are well established, some neurophysiological mechanisms of improved sleep remain unclear. Sleep spindles (SSs) provide sleep consolidation and are involved in the functional abnormalities in OSA. However, available data on SS activity improvement with PAP are limited and controversial. This pilot study aimed to evaluate the pattern of SS activity in patients with OSA after 6 months of PAP treatment. We performed a study of 17 males (mean age 53.4 years) with moderate OSA severity who underwent polysomnography (PSG) after 6 months of PAP treatment with compliance of at least 85%. 14 age-matched non-OSA males were used as controls. Quantitative sleep encephalographic (EEG) characteristics were assessed via power Spectral Analysis using the spectral analysis features of the GRASS-TELEFACTOR Twin PSG device, which include sigma activity (9–16 Hz) in the C3 and C4 EEG channels. The number, density, maximum amplitude, and mean frequency of SSs were calculated. Six months of PAP treatment partially normalized SSs activity patterns in patients with OSA. Elimination of nocturnal intermittent hypoxia was associated with an increase in relative sigma activity across the whole post-PAP treatment night: both number and density were increased, and both frequency and amplitude were decreased. The findings of this study demonstrated that PAP treatment may improve the respiratory arousal threshold during sleep and consolidate sleep by improving SS activity. These results suggest the neurophysiological mechanisms of sleep restoration following PAP treatment and the utility of quantitative measures of sleep EEG oscillations as functional markers of PAP improvement. We also suggest that a longer duration of PAP therapy is required to fully normalize the SS activity.
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© The Author(s), under exclusive licence to EDP Sciences, Springer-Verlag GmbH Germany, part of Springer Nature 2026
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.
