Correct!

4. 40%-60%

Obstructive sleep apnea (OSA) is frequently comorbid with insomnia (1). Studies have suggested that approximately 40%-60% of patients with OSA may have insomnia symptoms. Conversely, one-third to two-thirds of patients with insomnia may have at least mild OSA on polysomnography.

When the two disorders coexist, treatment of both should be considered. The treatment of OSA should follow the standard guidelines. Use of nonbenzodiazepine hypnotics such as eszopiclone may alleviate insomnia in patients with OSA (2). Eszopiclone use may also improve adherence to continuous positive airway pressure therapy in OSA patients (3).

References

1. Luyster FS, Buysse DJ, Strollo PJ. Comorbid insomnia and obstructive sleep apnea: challenges for clinical practice and research. J Clin Sleep Med 2010;6:196-204. [PubMed]
2. Rosenberg R, Roach JM, Scharf M, Amato DA. A pilot study evaluating acute use of eszopiclone in patients with mild to moderate obstructive sleep apnea syndrome. Sleep Med 2007;8:464-70. [CrossRef] [PubMed]  
3. Lettieri CJ, Shah AA, Holley AB, Kelly WF, Chang AS, Roop SA, Trial CPaP-TASAP. Effects of a short course of eszopiclone on continuous positive airway pressure adherence: a randomized trial. Ann Intern Med 2009;151:696-702. [CrossRef] [PubMed]

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