Sleep Apnea and Comorbid Insomnia

Sleep apnea and insomnia are two of the most prevalent sleep disorders, often coexisting and compounding the burden on patients’ quality of life. For sleep professionals, the challenge lies in unraveling the intertwined pathology of these conditions to provide effective treatment.

Given this complex interplay, it is crucial to identify and treat obstructive sleep apnea (OSA) as early as possible in patients presenting with insomnia symptoms. Home sleep testing (HST) offers a practical, accessible, and effective method for diagnosing OSA, particularly in patients who may be reluctant to undergo in-laboratory polysomnography.¹

By identifying and treating sleep apnea early, we can effectively address the root cause of many insomnia cases, leading to better patient outcomes and reducing the reliance on pharmacological interventions.

 Sleep Apnea and Secondary Insomnia

Insomnia is frequently categorized as primary or secondary, with the latter often being a consequence of another underlying condition, such as OSA. Many patients with OSA experience frequent awakenings during the night, leading to fragmented sleep. When they awaken, they often find themselves unable to return to sleep, leading to prolonged periods of wakefulness that can evolve into chronic insomnia.^2,3

This secondary insomnia, stemming from sleep apnea, is not merely a byproduct of nocturnal awakenings but also a reflection of disrupted sleep architecture and altered circadian rhythms. When patients repeatedly wake during the night, they become conditioned to expect awakenings, which can lead to anxiety about sleep. Over time, this anxiety exacerbates their insomnia, creating a vicious cycle that can be difficult to break without proper diagnosis and treatment.⁴

 Circadian Rhythm Disruption and Sleep-Wake Drives

The connection between sleep apnea and insomnia extends beyond nighttime awakenings. Many patients with OSA also have difficulty falling asleep, which can be attributed to disruptions in their circadian rhythm. The repeated nocturnal arousals and intermittent hypoxia associated with OSA can lead to dysregulation of the sleep-wake drives, further complicating the clinical picture.⁵

Circadian rhythm disruption in OSA patients often manifests as delayed sleep phase syndrome or difficulties in sleep maintenance. The interaction between the sleep drive, which builds up with prolonged wakefulness, and the circadian drive, which promotes alertness during the day and sleep at night, becomes disordered in these patients. As a result, the natural synchronization between these two processes is lost, leading to the onset of insomnia symptoms.⁶

 The Role of Insomnia Medications

Given the difficulty of managing insomnia in the context of untreated sleep apnea, it is not uncommon for patients to be prescribed hypnotic medications. However, while these medications may offer temporary relief, they often fail to address the underlying cause of the insomnia—namely, the untreated OSA. Moreover, reliance on these medications can perpetuate the cycle of insomnia by preventing patients from achieving the restorative sleep necessary to recalibrate their sleep-wake drives.⁷

There is a growing body of evidence suggesting that effective treatment of sleep apnea can lead to significant improvements in insomnia symptoms, often without the need for pharmacological intervention.⁸ Continuous positive airway pressure (CPAP) therapy, the gold standard for OSA treatment, has been shown to improve sleep architecture, reduce nocturnal awakenings, and restore the natural sleep-wake cycle.⁸ As such, treating sleep apnea may lead to remission of the insomnia, underscoring the importance of accurate diagnosis.

Considering HST as a First Step

For sleep professionals, the management of comorbid sleep apnea and insomnia presents a unique challenge that requires a nuanced approach. As evidence increasingly highlights the interconnected nature of these conditions, HST can be a useful first diagnostic step in patients presenting with insomnia and sleep apnea symptoms.

HST is not only cost-effective but also convenient for patients, allowing them to be tested in their natural sleep environment. It provides valuable data on respiratory events, sleep-disordered breathing, and nocturnal oxygen desaturation, which are key indicators of OSA. HST can also lend itself to mult-night sleep testing, which research has shown can be useful in COMISA patients.⁹ By confirming the presence of sleep apnea early, we can prioritize its treatment, potentially alleviating the associated insomnia without the need for long-term medication use.¹⁰

Furthermore, in cases where HST reveals OSA, we can tailor the therapeutic approach to address both conditions simultaneously. Initiating CPAP therapy or other appropriate treatments for OSA can lead to improvements in sleep continuity and reduce the overall burden of insomnia symptoms. This approach not only improves patient outcomes but also enhances adherence to therapy by addressing both the primary and secondary sleep disturbances.^11,12

By: Haramandeep Singh, MD

Source: SleepWorld Magazine September/October 2024

References

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