Sleep-wake misperception in sleep apnea patients undergoing diagnostic versus titration polysomnography

Abstract

Objective: Insomnia is commonly co-morbid with obstructive sleep apnea. Among patients reporting insomnia symptoms, sleep misperception occurs when self-reported sleep duration under-estimates objective measures. Misperception represents a clinical challenge since insomnia management is based entirely on patient self-report. We tested the hypothesis that misperception occurring in sleep apnea patients would improve with subsequent treatment.

Methods: We compared subjective sleep-wake reports with objective sleep in adults with obstructive sleep apnea (n=405) in two nights of polysomnography (diagnostic and treatment) within a median interval of 92 days.

Results: Sleep latency was generally over-estimated, while wake after sleep onset and number of awakenings were under-estimated. None of these estimations differed between diagnostic and treatment polysomnograms. We observed a large spectrum of total sleep time misperception values during the diagnostic polysomnogram, with one third of the cohort under-estimating their total sleep time by at least 60 min. Of those with >60 minute misperception, we observed improved total sleep time perception during treatment polysomnography. Improved perception correlated with improvements in self-reported sleep quality and response confidence. We found no polysomnogram or demographic predictors of total sleep time misperception for the diagnostic polysomnogram, nor did we find objective correlates of improved perception during titration.

Conclusion: Our results suggest that misperception may improve with treatment of obstructive sleep apnea in patients who also exhibit misperception. Within subject changes in misperception are consistent with misperception being, at least to some extent, a state characteristic, which has implications for management of patients with comorbid insomnia and sleep apnea.

Keywords: Paradoxical insomnia; Self-report; Subjective.

Figure 1. Mismatch between subjective and objective sleep-wake metrics

The distribution of values for mismatch (subjective – objective) on diagnostic PSG nights (open) and titration PSG nights (gray) is given for latency (panel A), TST (panel C), WASO (panel E), and # of awakenings (panel G). Adjacent to each of these metrics, the distribution of mismatch values is sub-categorized according to the self-reported insomnia symptoms. Brackets indicate statistical significance based on Kruskal-Wallis with Dunn's correction. Box and whisker plots show the median and the 25^th and 75^th percentile, with the error bars indicating the 10-90% range of the data. Latency, WASO, and # awakenings were all significantly different than zero in both diagnostic and titration studies.

Figure 2. Distribution of TST mismatch grouped by the degree of misperception in the diagnostic PSG

Frequency histogram plots of TST mismatch (subjective - objective; X-axis) is shown according to the degree of misperception during the diagnostic PSG (gray bars). The groups are separately shown according to those with >60 minutes of TST under-estimation (panel A), within 60 minutes of objective TST (panel B), or >60 minutes of over-estimation (panel C). In each panel, the distribution of TST mismatch during the titration PSG is also shown (black bars). Next to each panel, the box-and-whiskers plot of the same data is shown for visual comparison. The differences between diagnostic and titration studies were statistically significant for panels A and C (p<0.05, Friedman paired test; brackets).

Figure 3. Improved confidence and sleep quality during titration PSGs among those with misperception

Categorical patterns of confidence emphasizing extreme values (confidence = values of 6-7 on the 7-point scale; not confident = values of 1-2) indicates that only the subset who were not-confident in the diagnostic PSG and confident in the titration PSG showed a significant improvement in TST misperception (brackets; Kruskal-Wallis with Dunn's correction) (panel A). Panel B shows that pre-treatment sleep quality was lower in the group with misperception (>60 minute under-estimation of TST) than the group with <60 minutes of mismatch, and only the group with >60 minutes under-estimation showed significantly increased quality on PAP treatment (brackets; p<0.05, Kruskal-Wallis with Dunn's correction).