Sleep apnea as a cause of sleep misperception in elderly insomnia patients

Background: Often, polysomnography shows normal sleep efficiency in disaccord with a complaint of insomnia. Studies on polysomnographically-confirmed insomnia complaints in the elderly are scarce. Aims: To evaluate whether obstructive sleep apnea (OSA) is associated with sleep misperception in elderly insomnia patients. Methods: Records of patients aged 65 years or older who underwent a full-night sleep study to investigate insomnia symptoms were analyzed. Those with sleep efficiency≥85% were considered as sleep misperception cases and with sleep efficiency Results: Among 177 insomnia cases, 32 (18%) were classified as sleep misperception. The sleep misperception group was similar to the confirmed insomnia group in terms of anthropometry; no significant difference was found between groups in difficulty falling asleep or staying asleep, sleep quality, scores of the SCL-90-R, and ESS. The whole sample had mean apnea-hypopnea index (AHI) of 18±18 and 75 patients (42%) had AHI>15. The sleep misperception group had an AHI higher than the confirmed insomnia group (25±22 vs. 16±16, respectively; P=0.04). In binary logistic regression, controlling for sex, obesity, and ESS>10, the only significant regressor for sleep misperception is AHI>15 (odds ratio, OR=2.89, 95% confidence interval 1.26-6.65; P=0.01). Conclusions: The finding that elderly insomnia patients with sleep misperception have more severe OSA, independently of sleepiness, warrants future research on the participation of OSA severity in the mechanisms of sleep misperception.