Sleep spindle activity correlates with implicit statistical learning consolidation in untreated obstructive sleep apnea patients.

OBJECTIVE/BACKGROUND: The aim of this study was to examine the relationship between overnight consolidation of implicit statistical learning with spindle frequency EEG activity and slow frequency delta power during non-rapid eye movement (NREM) sleep in obstructive sleep apnea (OSA). PATIENTS/METHODS: Forty-seven OSA participants completed the experiment. Prior to sleep, participants performed a reaction time cover task containing hidden patterns of pictures, about which participants were not informed. After the familiarisation phase, participants underwent overnight polysomnography. 24 h after the familiarisation phase, participants performed a test phase to assess their learning of the hidden patterns, expressed as a percentage of the number of correctly identified patterns. Spindle frequency activity (SFA) and delta power (0.5-4.5 Hz), were quantified from NREM electroencephalography. Associations between statistical learning and sleep EEG, and OSA severity measures were examined. RESULTS: SFA in NREM sleep in frontal and central brain regions was positively correlated with statistical learning scores (r = 0.41 to 0.31, p = 0.006 to 0.044). In multiple regression, greater SFA and longer sleep onset latency were significant predictors of better statistical learning performance. Delta power and OSA severity were not significantly correlated with statistical learning. CONCLUSIONS: These findings suggest spindle activity may serve as a marker of statistical learning capability in OSA. This work provides novel insight into how altered sleep physiology relates to consolidation of implicitly learnt information in patients with moderate to severe OSA.

Gender differences in obstructive sleep apnoea, insomnia and restless legs syndrome in adults - What do we know? A clinical update.

Research in sleep medicine over the last decades has involved a broad variety of sleep disorders in both men and women. Gender differences have been identified in sleep physiology as well as in the three most common sleep disorders: obstructive sleep apnoea (OSA), insomnia and restless legs syndrome (RLS). However, research on gender differences in sleep medicine appears limited. This clinical review aims to give an updated overview of gender differences, in relation to prevalence, clinical presentation, treatment and quality of life in OSA, insomnia and RLS. Future research directions in the adult population will also be discussed.