Obstructive sleep apnea (OSA) is a frequent pathology with clinical implications. Its comorbidity with the complaint of insomnia is common, and has been increasingly studied in recent years, due to the multiple negative synergies highlighted by these two conditions, notably on all-cause excess mortality, cardiovascular risk, quality of life and sleep, as well as mental health. This comorbidity between insomnia and sleep apnea has recently been referred to as COMISA («co-morbid insomnia and sleep apnea»). In this article, we explore the relationship between OSA and insomnia, as well as its consequences and currently available treatments, through an analysis of the existing literature.