Both sleep spindles and slow oscillations have been implicated in sleep-dependent memory consolidation. Whereas spindles occur during both light and deep sleep, slow oscillations are restricted to deep sleep, raising the possibility of greater consolidation-related spindle involvement during deep sleep. We assessed declarative memory retention over an interval containing a nap and determined spindle density for light and deep sleep separately. In deep sleep, spindle density was considerably higher and showed a strong and robust positive correlation with retention. This relation was absent for light sleep, suggesting that the potentiating effects of spindles are tied to their co-occurrence with slow oscillations.

No abstract

No abstract

Obstructive sleep apnea (OSA) is associated with a lower cognitive and functional status in patients admitted for stroke rehabilitation. This underlines the importance of OSA as a probable prognostic factor, and calls for well-designed randomized controlled trials to study its treatability.

Recent findings suggest that sleep might serve a role in emotional coping. However, most findings are based on subjective reports of sleep quality, while the relation with underlying sleep physiology is still largely unknown. In this study, the impact of an emotionally distressing experience on the EEG correlates of sleep was assessed. In addition, the association between sleep physiological parameters and the extent of emotional attenuation over sleep was determined. The experimental set up involved presentation of an emotionally neutral or distressing film fragment in the evening, followed by polysomnographic registration of undisturbed, whole-night sleep and assessment of emotional reactivity to film cues on the next evening. We found that emotional distress induced mild sleep deterioration, but also an increase in the proportion of slow wave sleep (SWS) and altered patterning of rapid eye movement (REM) sleep. Indeed, while REM sleep occurrence normally increases over the course of the night, emotional distress flattened this distribution and correlated with an increased number of REM periods. While sleep deterioration was negatively associated to emotional attenuation over sleep, the SWS response was positively related to such attenuation and may form part of a compensatory response to the stressor. Interestingly, trait-like SWS characteristics also correlated positively with the extent of emotion attenuation over sleep. The combined results provide strong evidence for an intimate reciprocal relation between sleep physiology and emotional processing. Moreover, individual differences in subjects' emotional and sleep responses suggest there may be a coupling of certain emotion and sleep traits into distinct emotional sleep types.