Differences in electroencephalographic spectra during pre-sleep wakefulness, N1, and R sleep between comorbid insomnia and obstructive sleep apnea

Sleep electroencephalography biomarkers of cognition in obstructive sleep apnea

Obstructive sleep apnea has been associated with cognitive impairment and may be linked to disorders of cognitive function. These associations may be a result of intermittent hypoxaemia, sleep fragmentation and changes in sleep microstructure in obstructive sleep apnea. Current clinical metrics of obstructive sleep apnea, such as the apnea-hypopnea index, are poor predictors of cognitive outcomes in obstructive sleep apnea. Sleep microstructure features, which can be identified on sleep electroencephalography of traditional overnight polysomnography, are increasingly being characterized in obstructive sleep apnea and may better predict cognitive outcomes. Here, we summarize the literature on several major sleep electroencephalography features (slow-wave activity, sleep spindles, K-complexes, cyclic alternating patterns, rapid eye movement sleep quantitative electroencephalography, odds ratio product) identified in obstructive sleep apnea. We will review the associations between these sleep electroencephalography features and cognition in obstructive sleep apnea, and examine how treatment of obstructive sleep apnea affects these associations. Lastly, evolving technologies in sleep electroencephalography analyses will also be discussed (e.g. high-density electroencephalography, machine learning) as potential predictors of cognitive function in obstructive sleep apnea.

Effects of Continuous Positive Airway Pressure on Sleep State Misperception in Patients With Obstructive Sleep Apnea

BACKGROUND

Little is known regarding the effects of continuous positive airway pressure (CPAP) on sleep misperception in obstructive sleep apnea (OSA).

METHODS

Sleep state perception was measured by subtracting the objective total sleep time from the subjective sleep duration. Sleep underestimation and overestimation were defined as ± 60 minutes sleep perception. Insomnia and depressive symptoms were assessed using questionnaires. Finally, nonparametric statistical analyses were performed.

RESULTS

Of the 339 patients with OSA included in the study, 90 (26.5%) and 45 (13.3%) showed sleep underestimation and overestimation, respectively. Overall, a significant underestimation of sleep was noted during CPAP titration comparing to a diagnostic PSG (P < 0.001). OSA patients with insomnia or depressive symptoms did not show any changes in sleep perception between diagnostic and CPAP titration studies, whereas those without insomnia or depressed mood showed significantly underestimated sleep duration during CPAP titration. Patients with OSA and either underestimated or overestimated misperception showed perceptual improvements during CPAP titration regardless of the presence of insomnia or depressive symptoms. However, of 204 patients with normal sleep perception, 138 (67.6%) and 10 (4.9%) had underestimation and overestimation of sleep during CPAP titration.

CONCLUSION

CPAP titration may improve sleep perception with moderate to severe OSA who have sleep misperception. However, CPAP titration may result in sleep misperception especially underestimation of sleep in those who have normal sleep perception.

Parasomnias related to shift work disorder among medical residents during the first year of training in Mexico

Shift work disorder (SWD) may affect medical residents because their workload, academic demands and extended work hours. This condition set residents at risk of more sleep disorders. The study compared parasomnias among residents with and without shift work disorder (SWD) and weighed their relative risk (RR) for each parasomnia. One hundred twenty-six residents participated in the study. The Munich Parasomnia Screening questionnaire and the Barger Questionnaire for SWD were used for the screening of parasomnias and SWD, respectively. Means and percentages of studied variables were compared between groups. Relative risk (RR) was calculated for each type of parasomnia. The more frequent parasomnias in residents with SWD the RR (and 95% confidence intervals) were: sleep terrors, 5.60 (1.84-17.01); confusional arousals, 3.73 (1.84-7.56); sleep paralysis, 3.27 (1.53-6.93); hypnagogic/hypnopompic hallucinations, 2.55 (1.03-6.28); somniloquies, 2.45 (1.21-4.92); and nightmares, 2.01 (1.54-2.62). Our data suggest that residents who experience SWD may be at risk of having lower threshold for the occurrence of rapid eye movement (REM) and non-REM (NREM) sleep parasomnias. Additional research is needed to confirm these results, and to further identify the contribution to this association.

Factors associated with sleep state misperception in patients with obstructive sleep apnea

PURPOSE

Little is known regarding the prevalence of sleep state misperception and the factors related to this in patients with obstructive sleep apnea (OSA).

METHODS

This retrospective study included patients with OSA defined by an apnea-hypopnea index (AHI) of ≥ 5 and used the Insomnia Severity Index (ISI), the Epworth sleepiness scale, the Patient Health Questionnaire-9, and the Generalized Anxiety Disorder-7. Underestimation and overestimation of sleep state perception were defined as < 80% and > 120%, respectively, of the ratio between subjective and objective total sleep time. An ISI score > 14 indicated clinically significant insomnia and an AHI ≥ 30 indicated severe OSA. A multinomial logistic regression was conducted with the category of sleep state perception as an outcome variable.

RESULTS

Of the 707 patients with OSA, underestimation and overestimation of sleep state perception were noted in 22.5% and 10.6% of subjects, respectively. The median absolute differences (and percentages of the ratio) between subjective and objective total sleep time were 116 min (66.9%) and 87 min (127.3%) in the underestimated and overestimated perception groups, respectively. In the adjusted model, the underestimated group was more likely to have an ISI score > 14 (OR = 1.812, P = .006). The overestimated group was more likely to be older (OR = 1.025, P = .025) and has severe OSA (OR = 1.729, P = .035).

CONCLUSIONS

There are two patterns of sleep state misperception in patients with OSA: underestimation associated with comorbid insomnia symptoms and overestimation associated with severe OSA. These findings enhance understanding of the pathophysiology of sleep state misperception in patients with OSA.