We study correlation properties of the magnitude and the sign of the increments in the time intervals between successive heartbeats during light sleep, deep sleep, and rapid eye movement (REM) sleep using the detrended fluctuation analysis method. We find short-range anticorrelations in the sign time series, which are strong during deep sleep, weaker during light sleep, and even weaker during R...

Recently, many lines of investigation in neuroscience and statistical physics have converged to raise the hypothesis that the underlying pattern of neuronal activation which results in electroencephalography (EEG) signals is nonlinear, with self-affine dynamics, while scalp-recorded EEG signals themselves are nonstationary. Therefore, traditional methods of EEG analysis may miss many properties...

Sound is the most adequate external stimulus for studying information processes in the brain during falling asleep and at different sleep stages. Common procedure of analysis of the event-related potentials (ERPs) averaged for a group of subjects has some drawbacks because of the ERP interindividual variability. Therefore in our work, we determined parameters of the auditory ERP components sele...

The sleep homeostatic response significantly affects the state of anesthesia. In addition, sleep recovery may occur during anesthesia, either via a natural sleep-like process to occur or via a direct restorative effect. Little is known about the effects of isoflurane anesthesia on sleep homeostasis. We investigated whether 1) isoflurane anesthesia could provide a sleep-like process, and 2) the ...

STUDY OBJECTIVES Functional significance of stage 2 sleep spindle activity for declarative memory consolidation. DESIGN Randomized, within-subject, multicenter. SETTING Weekly sleep laboratory visits, actigraphy, and sleep diary (4 weeks). PARTICIPANTS Twenty-four healthy subjects (12 men) aged between 20 and 30 years. INTERVENTIONS Declarative memory task or nonlearning control task be...

The spatial organization of nonlinear interactions between different brain regions during the first NREM sleep stage is investigated. This is achieved via consideration of four bipolar electrode derivations, Fp1F3, Fp2F4, O1P3, O2P4, which are used to compare anterior and posterior interhemispheric interactions and left and right intrahemispheric interactions. Nonlinear interdependence is detec...

Apnea and arousal are modulated with sleep stage, and swallowing may interfere with respiratory rhythm in infants. We hypothesized that swallowing itself would display interaction with sleep state. Concurrent polysomnography and measurement of swallowing allowed time-matched analysis of 3,092 swallows, 482 apneas, and 771 arousals in 17 infants aged 1-34 wk. The mean rates of swallowing, apnea,...

STUDY OBJECTIVES Aim of the present study was to assess changes in arousal rates after selective slow-wave (SWS) and total sleep deprivations. DESIGN Two-way mixed design comparing the arousal index (Al), as expressed by the number of EEG arousals divided by sleep duration, in totally or selectively sleep deprived subjects. SETTING Sleep laboratory. PATIENTS OR PARTICIPANTS Nineteen norma...

OBJECTIVES To evaluate the feasibility of using unattended, portable polysomnography (PSG) to measure sleep among patients in the medical intensive care unit (MICU). BACKGROUND Accurate measurement of sleep is critical to studies of MICU sleep deprivation. Although PSG is the gold standard, there is limited data regarding the feasibility of utilizing unattended, portable PSG modalities in the...

Electroencephalograph (EEG) analysis enables the dynamic behavior of the brain to be examined. If the behavior is nonlinear then nonlinear tools can be used to glean information on brain behavior, and aid in the diagnosis of sleep abnormalities such as obstructive sleep apnea syndrome (OSAS). In this paper the sleep EEGs of a set of normal children and children with mild OSAS are evaluated for ...