Sleep Instability in Paradoxical Insomnia is Associated with Perception of Sleep

Objective The main clinical characteristics that diversify paradoxical insomniacs from objective insomnia patients remain unclear. The current study systematically examined the difference in sleep-related, subjective-and objective parameters between insomnia patients with or without misperception. Methods Patients who reported having poor sleep quality (subjective sleep efficiency; SE ≤ 85%) on both weekends and weekdays and difficulty falling asleep in the Sleep Heart Health Study were examined in this study. Patients with objective SE ≤ 85% and > 85% were then classified as objective insomnia (n = 58) and paradoxical insomnia (n = 61), respectively. The differences in demographic data, subjective sleep quality, daytime function, and objective sleep architecture measured by polysomnography, were assessed between the groups. Results Though there were no significant group differences in the demographics between objective insomniacs and paradoxical insomniacs, paradoxical insomniacs reported significantly poorer daytime function than patients with objective insomnia. Moreover, paradoxical insomniacs’ subjective sleep evaluation on recording day was significantly higher than habitual reports. The main finding from this research was that the transition indices from stage N3 to stage N2 or N1 was significantly different between the two groups, which could indicate that sleep instability may be a factor in leading paradoxical insomnia patients to underestimate their sleep efficiency. Conclusions Our findings indicated a possible link between sleep misperception and the microstructure of sleep, specifically the sleep-state instability. The interplay between the neurobiology of sleep instability and perception of sleep needs further investigation. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study did not receive any funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: National Sleep Research Resource (NSRR) approved. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data produced in the present work are contained in the manuscript