Co-morbid insomnia and sleep apnea (COMISA) is a highly prevalent and debilitating disorder, which results in additive impairments to patients’ sleep, daytime functioning, and quality of life, and complex diagnostic and treatment decisions for clinicians. Although the presence of COMISA was first recognized by Christian Guilleminault and colleagues in 1973, it received very little research attention for almost three decades, until the publication of two articles in 1999 and 2001 which collectively reported a 30%–50% co-morbid prevalence rate, and re-ignited research interest in the field. Since 1999, there has been an exponential increase in research documenting the high prevalence, common characteristics, treatment complexities, and bi-directional relationships of COMISA. Recent trials indicate that co-morbid insomnia symptoms may be treated with cognitive and behavioral therapy for insomnia, to increase acceptance and use of continuous positive airway pressure therapy. Hence, the treatment of COMISA appears to require nuanced diagnostic considerations, and multi-faceted treatment approaches provided by multi-disciplinary teams of psychologists and physicians. In this narrative review, we present a brief overview of the history of COMISA research, describe the importance of measuring and managing insomnia symptoms in the presence of sleep apnea, discuss important methodological and diagnostic considerations for COMISA, and review several recent randomized controlled trials investigating the combination of CBTi and CPAP therapy. We aim to provide clinicians with pragmatic suggestions and tools to identify, and manage this prevalent COMISA disorder in clinical settings, and discuss future avenues of research to progress the field.

Background: Increased mortality has been reported in people with insomnia and in those with obstructive sleep apnoea (OSA). However, these conditions commonly co-occur and the combined effect of comorbid insomnia and sleep apnoea (COMISA) on mortality risk is unknown. This study used Sleep Heart Health Study (SHHS) data to assess associations between COMISA and all-cause mortality risk.Methods: Insomnia was defined as difficulties falling asleep, maintaining sleep and/or early morning awakenings from sleep ≥16 times per month, and daytime impairments. OSA was defined as an apnoea–hypopnoea index ≥15 events·h⁻¹. COMISA was defined if both conditions were present. Multivariable adjusted Cox proportional hazards models were used to determine the association between COMISA and all-cause mortality (n=1210) over 15 years of follow-up.Results: 5236 participants were included. 2708 (52%) did not have insomnia/OSA (reference group), 170 (3%) had insomnia-alone, 2221 (42%) had OSA-alone and 137 (3%) had COMISA. COMISA participants had a higher prevalence of hypertension (OR 2.00, 95% CI 1.39–2.90) and cardiovascular disease (CVD) (OR 1.70, 95% CI 1.11–2.61) compared with the reference group. Insomnia-alone and OSA-alone were associated with higher risk of hypertension but not CVD compared with the reference group. Compared with the reference group, COMISA was associated with a 47% (hazard ratio 1.47, 95% CI 1.06–2.07) increased risk of mortality. The association between COMISA and mortality was consistent across multiple definitions of OSA and insomnia.Conclusions: COMISA was associated with higher rates of hypertension and CVD at baseline, and an increased risk of all-cause mortality compared with no insomnia/OSA.

Study Objectives: Insomnia and obstructive sleep apnea (OSA) commonly co-occur which makes OSA difficult to treat with continuous positive airway pressure (CPAP). We conducted a randomized controlled trial in participants with OSA and co-occurring insomnia to test the hypothesis that initial treatment with cognitive and behavioral therapy for insomnia (CBT-i), versus treatment as usual (TAU) would improve insomnia symptoms and increase subsequent acceptance and use of CPAP.Methods: One hundred and forty-five participants with OSA (apnea-hypopnea index ≥ 15) and comorbid insomnia were randomized to either four sessions of CBT-i, or TAU, before commencing CPAP therapy until 6 months post-randomization. Primary between-group outcomes included objective average CPAP adherence and changes in objective sleep efficiency by 6 months. Secondary between-group outcomes included rates of immediate CPAP acceptance/rejection, and changes in; sleep parameters, insomnia severity, and daytime impairments by 6 months.Results: Compared to TAU, participants in the CBT-i group had 61 min greater average nightly adherence to CPAP (95% confidence interval [CI] = 9 to 113; p = 0.023, d = 0.38) and higher initial CPAP treatment acceptance (99% vs. 89%; p = 0.034). The CBT-i group showed greater improvement of global insomnia severity, and dysfunctional sleep-related cognitions by 6 months (both: p < 0.001), and greater improvement in sleep impairment measures immediately following CBT-i. There were no between-group differences in sleep outcomes, or daytime impairments by 6 months.Conclusions: In OSA participants with comorbid insomnia, CBT-i prior to initiating CPAP treatment improves CPAP use and insomnia symptoms compared to commencing CPAP without CBT-i. OSA patients should be evaluated for co-occurring insomnia and considered for CBT-i before commencing CPAP therapy.Clinical Trial: Treating comorbid insomnia with obstructive sleep apnea (COMSIA) study: A new treatment strategy for patients with combined insomnia and sleep apnea, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=365184 Australian New Zealand Clinical Trials Registry: ACTRN12613001178730. Universal Trial Number: U1111-1149-4230.