Role of sleep misperceptions in relationship between co-morbid insomnia and obstructive sleep apnea

Objectives: Co-morbid insomnia occurs in 40–60% of Obstructive Sleep Apnea (OSA) patients. To develop effective treatments for this co-morbid condition, it is important to investigate factors causing this high co-occurrence. Insomnia is commonly associated with under estimations of total sleep time, and overestimations of time spent awake, resulting from patients misperceiving prior sleep as wakefulness. OSA is characterised by sleep fragmentation, increased light sleep, and oxygen desaturations throughout the night. It is possible that the sleep fragmentation resulting from OSA predisposes patients to awaken during the night and misperceive their sleep as wakefulness. This may lead to the development of a subjective insomnia complaint. Methods: Participants included 116 individuals with OSA (AHI>15)and insomnia (ICSD-2) who completed an overnight polysomnographic sleep study, and sleep diary. Objective sleep time was subtracted from diary sleep time to create ‘misperception’ scores. Relationships between these misperception scores, and several indices of OSA-severity were examined with correlational analyses. Results: Misperceptions of total sleep time were significantly positively correlated with AHI (r(114) = 0.21, P = 0.03), arousal index (r(115) = 0.22, P = 0.02), percent stage 1 sleep (r(115) = 0.22, P = 0.02), and percent of time with oxygen saturation less than 90% (r(115) = 0.19, P = 0.04).Conclusions: These results indicate that greater under estimations of sleep are associated with night-time manifestations of OSA severity, including increased AHI, light sleep, and time with low oxygen saturation. The sleep fragmentation caused by OSA may predispose patients to underestimate their sleep, and develop an insomnia complaint. This may be one, of several pathways contributing to the co-occurrence of insomnia and OSA. Disclosure: Research Funded by NHMRC Grant: 1049591.