Patient Report:  

The Effects of Continuous Positive Airway Pressure (CPAP) Therapy on Sleep Quality, Particularly Deep Sleep and Arousals

Saar Lanir, PhD, Neuroscientist and sleep researcher at Dormotech Medical.

Introduction 

Sleep-related breathing disorders (SRBDs), including obstructive sleep apnea (OSA), are highly prevalent and associated with substantial morbidity (1). The American Academy of Sleep Medicine (AASM) and the European Respiratory Society recommend continuous positive airway pressure (CPAP) therapy as the first-line treatment for moderate-to-severe OSA due to its proven efficacy in reducing apneic events, improving oxygenation, and alleviating daytime sleepiness (2). While CPAP’s primary role in normalizing respiratory parameters during sleep is well established, its broader effects on sleep architecture and non-respiratory sleep quality metrics remain less well characterized, particularly in the home environment. 

Human sleep comprises cycles of non-rapid eye movement (NREM) and rapid eye movement (REM) stages (3). NREM includes stages N1, N2, and N3, with stage N3 (slow-wave sleep) representing the deepest and most restorative phase. N3 sleep plays a vital role in tissue repair, immune function, and memory consolidation (4). Sleep fragmentation, characterized by frequent arousals, disrupts these processes, even when total sleep time appears sufficient (5). Restoring N3 and minimizing arousals are therefore critical for achieving high-quality, restorative sleep. 

This case study leverages the capability of type 2 polysomnography (PSG) conducted in the patient’s home—a setting that preserves naturalistic sleep patterns while enabling comprehensive EEG-based analysis. We examined changes in deep sleep (N3) and arousal indices across two consecutive nights: one without CPAP and one with CPAP. This approach highlights not only CPAP’s potential to improve non-respiratory sleep quality but also demonstrates the clinical utility of home-based type 2 PSG in evaluating sleep architecture in a real-world environment. 

Methods 

This case report describes the sleep assessment of a single participant with mild obstructive sleep apnea (OSA) using type 2 home polysomnography (PSG). Data were collected over two consecutive nights in the participant’s home environment. 

On the first night, baseline sleep was recorded without CPAP therapy. On the second night, CPAP was applied using a device titrated to eliminate respiratory events. Sleep studies were conducted using the Dormotech DormoVision system (6), which provides comprehensive polysomnographic monitoring including three frontal EEG channels, two electrooculogram (EOG) channels, chin and leg electromyograms (EMG), and respiratory parameters (nasal/oral airflow, thoracic and abdominal effort, oximetry, snore microphone, and body/head position sensors). 

Sleep staging and arousal scoring were performed according to American Academy of Sleep Medicine (AASM) criteria (7). Deep sleep (N3) percentage and absolute duration, along with arousal counts and indices (spontaneous and respiratory-related), were analyzed to assess changes in sleep architecture and continuity between the two nights. 

Results 

First Night: Without CPAP

During the first night, the patient exhibited mild obstructive sleep apnea, with a total of 60 respiratory events (20 apneas and 40 hypopneas), resulting in an Apnea-Hypopnea Index (AHI) of 9.8 events/hour. This value falls within the mild severity range; however, the burden of obstruction was disproportionately higher during REM sleep (REM AHI: 21.5 events/hour) compared to NREM sleep (NREM AHI: 7.6 events/hour). Minimum oxygen saturation dropped to 85%, with a cumulative 7.9 minutes spent below 90%. 

Sleep architecture revealed preserved sleep efficiency (96.1%), yet restorative deep sleep (N3) was markedly reduced to 7% of total sleep time—substantially lower than normative reference values. REM sleep accounted for 16% of total sleep time. Importantly, frequent arousals were observed, with a total of 30 events (24 during NREM and 6 during REM), yielding an elevated arousal index of 4.9 events/hour. The majority of arousals (28) were temporally associated with respiratory disturbances, while only two were classified as spontaneous. 

Second Night: With CPAP 

On the second night, application of CPAP therapy effectively abolished obstructive respiratory events, with only 2 apneas and 6 hypopneas detected (AHI: 1.1 events/hour). Oxygen saturation remained stable throughout the night, and no time was spent with saturation levels below 90%. 

The patient’s sleep architecture demonstrated substantial improvement. The proportion of deep sleep (N3) nearly doubled, rising to 13% of total sleep time, while REM sleep increased to 19%. Sleep efficiency improved further to 98.0%. Most notably, there was a striking reduction in arousals: only three were observed in total (two during NREM and one during REM), yielding a markedly reduced arousal index of 0.3 events/hour. All arousals were spontaneous, with no respiratory-related arousals recorded. 

Comparison of Two Studies 

The comparison between the two nights underscores the profound impact of CPAP therapy, even in the context of mild obstructive sleep apnea. Beyond the resolution of respiratory events and associated oxygen desaturations, CPAP promoted more consolidated and restorative sleep. This was evidenced by a substantial increase in slow-wave (N3) sleep and a near elimination of arousals, reflecting enhanced sleep continuity and depth. 

These findings emphasize that CPAP therapy not only addresses apneic events but also improves overall sleep quality by reducing sleep fragmentation and supporting healthy sleep architecture. Such benefits highlight the potential value of CPAP even in mild cases of sleep-disordered breathing, where traditional emphasis on AHI alone might underestimate the clinical impact. 

Conclusion 

This case illustrates how effective intervention with CPAP can positively influence both physiological and structural aspects of sleep, even for individuals with mild OSA. By achieving near-total elimination of respiratory-related disturbances and markedly improving sleep architecture, CPAP therapy has the potential to enhance not only objective sleep parameters but also, ultimately, the overall well-being and quality of life for those affected by sleep-disordered breathing. 

Equally important is the role of Type 2 sleep testing in the comprehensive assessment and monitoring of such cases. Type 2 studies, which provide detailed polysomnographic data in the home setting, are invaluable for accurately diagnosing sleep-disordered breathing, assessing the severity of events, and evaluating the impact of interventions like CPAP. By enabling longitudinal monitoring, Type 2 testing ensures that therapeutic adjustments can be tailored to the individual’s evolving needs, supporting optimal outcomes and long-term sleep health. 

References  

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