INTRODUCTION Sleep in intensive care unit (ICU) patients is severely altered. In a large proportion of critically ill patients, conventional sleep electroencephalogram (EEG) patterns are replaced by atypical sleep. On the other hand, some non-sedated patients can display usual sleep EEG patterns. In the latter, sleep is highly fragmented and disrupted and conventional rules may not be optimal. ...

Sleep is regulated by homeostatic and circadian processes [1]. In mammals, homeostatic sleep pressure is reflected by electroencephalogram (EEG) slow-wave activity (SWA, EEG power density between ~1 and 4 Hz) in undisturbed non-rapid eye movement (NREM) sleep. In all mammalian species investigated until now, not only the amount of sleep, but also SWA in NREM sleep increases after sleep deprivat...

126 FROM THE PERSPECTIVE OF A SLEEP RESEARCHER ALL THE ACTION SEEMS TO OCCUR DURING SLEEP WHILE WAKING IS THIS OTHER, UNAPPRECIATED AND undifferentiated state that simply fills the time between periods of sleep. Sleep comes in two flavors: REM sleep and non-REM (NREM) sleep. One defining characteristic of the latter is the presence of delta oscillations (1-4Hz) in the EEG. The prevalence and am...

Learning-dependent increases in sleep spindle density have been reported during nocturnal sleep immediately after the learning session. Here, we investigated experience-dependent changes in daytime sleep EEG activity after declarative learning of unrelated word pairs. At weekly intervals, 13 young male volunteers spent three 24 h sessions in the laboratory under carefully controlled homeostatic...

Sleep stages classification is one of the most important methods for diagnosis in psychiatry and neurology. In this paper, a combination of three kinds of classifiers are proposed which classify the EEG signal into five sleep stages including Awake, N-REM (non-rapid eye movement) stage 1, N-REM stage 2, N-REM stage 3 and 4 (also called Slow Wave Sleep), and REM. Twenty-five all night recordings...

In previous sleep studies, it has been demonstrated that Poincare plots of RR intervals, which provide a beat to beat dynamic measure of heart rate variability, have distinctive and characteristic patterns according to sleep stages. This study was designed to evaluate the temporal relationship between heart rate variability and sleep electroencephalographic activity (EEG) by using the Pearson's...

New multichannel descriptors of EEG activity: complexity (omega), total power (zeta) and generalized frequency (phi) were applied to whole night sleep analysis in 11 healthy subjects. The values of omega and phi decreased systematically from waking to slow wave sleep, and increased systematically in consecutive NREM-REM sleep cycles. The changes of zeta were opposite to omega and phi. These des...

Specific patterns of brain activity during sleep and waking are recorded in the electroencephalogram (EEG). Time-frequency analysis methods have been widely used to analyse the EEG and identified characteristic oscillations for each vigilance state (VS), i.e., wakefulness, rapid-eye movement (REM) and non-rapid-eye movement (NREM) sleep. However, other aspects such as change of patterns associa...

Rapid eye movement sleep in males is characterized by penile erection along with EEG desynchronization, muscle atonia, ponto-geniculo-occipital waves, and rapid eye movements (REM). The central neural mechanisms regulating sleep related erections (SREs) are not known. Recently, the lateral preoptic area has been shown to contribute in sleep-related erectile mechanisms. The present study was con...

Permutation entropy and order patterns in an EEG signal have been applied by several authors to study sleep, anesthesia, and epileptic absences. Here, we discuss a new version of permutation entropy, which is interpreted as distance to white noise. It has a scale similar to the well-known χ2 distributions and can be supported by a statistical model. Critical values for significance are provided...