brain sciences Review Co-Morbid Insomnia and Sleep Apnea (COMISA): Prevalence, Consequences, Methodological Considerations, and Recent Randomized Controlled Trials Alexander Sweetman 1,* , Leon Lack 2 and Célyne Bastien 3 1 The Adelaide Institute for Sleep Health: A Flinders Centre of Research Excellence, Box 6 Mark Oliphant Building, 5 Laffer Drive, Bedford Park, Flinders University, Adelaide 5042, South Australia, Australia 2 The Adelaide Institute for Sleep Health: A Flinders Centre of Research Excellence, College of Education Psychology and Social Work, Flinders University, Adelaide 5042, South Australia, Australia; leon.lack@flinders.edu.au 3 School of Psychology, Félix-Antoine-Savard Pavilion, 2325, rue des Bibliothèques, local 1012, Laval University, Quebec City, QC G1V 0A6, Canada;
[email protected] * Correspondence: alexander.sweetman@flinders.edu.au; Tel.: +61-8-7421-9908 Received: 15 November 2019; Accepted: 10 December 2019; Published: 12 December 2019 Abstract: 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.