Sleep, a vital process of human being, is carefully orchestrated by the brain and consists of cyclic transitions between rapid eye movement (REM) and non-REM (NREM) sleep. Autonomic tranquility during NREM sleep is characterized by vagal dominance and stable breathing, providing an opportunity for the cardiovascular-neural axis to restore homeostasis, in response to use, distress or fatigue inflicted during wakefulness. Abrupt irregular swings in sympathovagal balance during REM sleep act as phasic loads on the resting cardiovascular system. Any causes of sleep curtailment or fragmentation such as sleep restriction, sleep apnea, insomnia, periodic limb movements during sleep, and shift work, not only impair cardiovascular restoration but also impose a stress on the cardiovascular system. Sleep disturbances have been reported to play a role in the development of stroke and other cardiovascular disorders. This review aims to provide updated information on the role of abnormal sleep in the development of stroke, to discuss the implications of recent research findings, and to help both stroke clinicians and researchers understand the importance of identification and management of sleep pathology for stroke prevention and care.

Summary:Purpose: Application of independent component analysis (ICA) to interictal EEGs and to event-related potentials has helped noise reduction and source localization. However, ICA has not been used for the analysis of ictal EEGs in partial seizures. In this study, we applied ICA to the ictal EEGs of patients with medial temporal lobe epilepsy (TLE) and investigated whether ictal components can be separated and whether they indicate correct lateralization.Methods: Twenty-four EEGs from medial TLE patients were analyzed with the extended ICA algorithm. Among the resultant 20 components in each EEG, we selected components with an ictal nature and reviewed their corresponding topographic maps for the lateralization. We then applied quantitative methods for the verification of increased quality of the reconstructed EEGs.Results: All ictal EEGs were successfully decomposed into one or more ictal components and nonictal components. After EEG reconstruction with exclusion of artifacts, the lateralizing power of the ictal EEG was increased from 75 to 96%.Conclusions: ICA can separate successfully the manifold components of ictal rhythms and can improve EEG quality. Key Words: Independent component analysis-Ictal component-Ictal EEG-Medial temporal lobe epilepsyArtifact.EEG recording is an essential step to localize irritative and ictal-onset zones, especially when epilepsy surgery is being considered. To localize the ictal-onset zone, a well-trained epileptologist visually inspects the EEG recordings. Identification of an unambiguous ictal-onset zone is often difficult because of unwanted artifacts arising from muscle contraction or eye movements. Recently a new data-processing technique, independent component analysis (ICA), was developed for the purpose of resolving multiple mixtures of data into statistically independent components (1,2). If we apply this method of analysis to EEG data, the EEG can be decomposed into spatiotemporal components that have fixed potential field distributions and maximally independent waveforms. The method has been found to be quite successful in separating artifacts or noisy components from the multichannel interictal EEG (3), recordings of event-related potentials (4), and functional magnetic resonance imaging (MRI) (5).We applied ICA to multichannel ictal EEG recordings in medial temporal lobe epilepsy (TLE). The ICA transforms the multichannel EEG data into an equal number of spatial patterns and their associated temporal waveforms, which are statistically independent of each other. The purpose of this study was to provide answers for the following two questions: Can ICA separate successfully ictal rhythms from noisy ictal EEGs of partial seizures? Can ICA help to lateralize medial TLE? MATERIALS AND METHODSWe applied ICA to 11 ictal EEGs from seven right medial TLE patients and to 13 EEGs from seven left medial TLE patients. All patients had been seizure free for more than a year after standard anterior temporal lobectomy with amygdalohippocampectomy. The diagnosis of each patien...