Comorbid insomnia and sleep apnea: characterization of the syndrome and understanding its associations with comorbid sleep conditions.

Purpose: Obstructive sleep apnea (OSA) is traditionally associated with excessive daytime sleepiness. Insomnia is characterized by hyperarousal, and is seen as a predominant feature in a subgroup of patients with OSA. The aim of this study was to describe the prevalence of comorbid insomnia and sleep apnea (COMISA) in a sleep apnea population and to characterize its features.

Methods: This was a chart review of patients who underwent overnight polysomnography (PSG). All patients completed questionnaires with the Epworth Sleepiness Scale (ESS), and symptoms of insomnia and other sleep-related comorbidities. Patients with OSA on the PSG were included.

Results: A total of 296 patients with OSA were included, of which 80% reported at least 1 major symptom of insomnia: 57% reported sleep onset insomnia, 68% sleep maintenance insomnia, and 48% had early morning awakenings. COMISA (OSA plus 2 or more major symptoms of insomnia) was seen in 63%. These patients were more likely to report an abnormal ESS score, gastroesophageal reflux (GER), and restless legs (RL) than those without; no difference was seen in self-reported sleep bruxism. Among the patients with COMISA, 85% reported at least 1 representative symptom of psychophysiological insomnia (PPI); each of the 5 PPI symptoms was present in at least 40% of patients with COMISA.

Conclusions: Insomnia is extremely prevalent in our population of patients with OSA, accompanied by daytime sleepiness and symptoms of PPI, GER, and RL. Further study is needed to determine the interactions between symptoms and OSA treatments in these patients.