Occurrence of insomnia among patients with diagnosed obstructive sleep apnea

Obstructive sleep apnea (OSA) is a common problem. Excessive daytime sleepiness raises a suspicion of OSA, which can be confirmed by polysomnography (PSG). Insomnia, in patients with OSA, often manifests itself as excessive daytime drowsiness. The incidence of insomnia among patients with OSA differs in different studies. Thus, we investigated the incidence of insomnia among our patients. We included 120 patients who underwent a workup due to a suspicion of OSA in the Polysomnography Laboratory, Department of Otolaryngology, Medical University of Warsaw, Poland. Patients completed the Athens Insomnia Scale (AIS). All-night PSG was done with 14-channel recordings (Grass®, USA). The severity of OSA was classified according to the apnea-hypopnea index (AHI) values. There were 96 patients with OSA and 24 patients without OSA who served as controls (their sleep disorders and daytime drowsiness were not caused by OSA). The total AIS scores tended to indicate insomnia in the entire sample and in all different subgroups. The mean AIS score was significantly different between the subgroups differing in the severity of apnea. The mean AIS score correlated significantly with sleep latency, latent sleep, and N2 latency. The mean AIS score did not correlate significantly with the AHI. In conclusion, in patients with OSA, insomnia, measured with the AIS, was associated with the severity of apnea, although this relationship was weak.