Slow-wave activity and sigma activities are associated with psychomotor development at 8 months of age.

Study Objectives: The electrophysiological properties of non-rapid eye movement sleep (NREM) EEG are homeostatically modulated on global and local use-dependent levels. Furthermore, the local NREM quality reflects age-dependent brain maturation and individual, age-independent, and psychomotor potential. Cortical maturation and its electrophysiological marker, Slow-wave activity (SWA), as well as sleep spindles are known to change in topography and quality during the early years of life, but their associations with psychomotor development in infants are unknown.

Prolonged partial obstruction during sleep is a NREM phenomenon.

Objective: Prolonged partial obstruction (PPO) is a common finding in sleep studies. Although not verified, it seems to emerge in deep sleep. We study the effect of PPO on sleep architecture or sleep electroencephalography (EEG) frequency.

Local changes in computational non-rapid eye movement sleep depth in infants.

Objective: Deep NREM sleep and its hallmark EEG phenomenon slow wave activity (SWA) are under homeostatic control in adults. SWA is also locally regulated as it increases in the brain areas that have been used intensively. Moreover, in children, SWA is a marker of cortical maturation.

Local Differences in Computational Sleep Depth Parameters in Healthy School-aged Children.

Objective: Slow wave sleep in children reflects several processes, such as sleep pressure, synaptic density, and cortical maturation. Deep sleep in children is abundant and our aim was to discover whether examining electroencephalography (EEG) mean frequency would help separate these processes.

Methods: Sleep EEG of 28 generally healthy 7- to 11-year-old children (14 first graders, 14 third graders, 14 girls, 14 boys) was analyzed.

Sleep During Menopausal Transition: A 6-Year Follow-Up.

Study Objectives: Menopausal transition is associated with increased dissatisfaction with sleep, but the effects on sleep architecture are conflicting. This prospective 6-year follow-up study was designed to evaluate the changes in sleep stages and sleep continuity that occur in women during menopausal transition.

Methods: Sixty women (mean age 46.

CPAP Treatment Partly Normalizes Sleep Spindle Features in Obstructive Sleep Apnea.

. Obstructive sleep apnea (OSA) decreases sleep spindle density and frequency. We evaluated the effects of continuous positive airway pressure (CPAP) treatment on different features of sleep spindles.

Evaluation of the different sleep-disordered breathing patterns of the compressed tracheal sound.

Objective: Suitability of the compressed tracheal sound signal for screening different sleep-disordered breathing patterns was evaluated. The previous results suggest that the plain pattern in the compressed sound signal represents mostly normal, unobstructed breathing, the thick pattern consists of periodic apneas/hypopneas and during the thin pattern, flow limitation in the nasal cannula signal is abundant.

Methods: Twenty-seven patients underwent a polysomnography with a tracheal sound and oesophageal pressure monitoring.

Identification of deep sleep and awake with computational EEG measures.

The objective of the present work was to examine identification of deep sleep and awake with computational analysis of sleep EEG traces from central brain regions. All-night EEG traces from a total of 56 male subjects, 22 healthy control subjects and 34 age-matched apnea patients, were examined. A spectral mean frequency measure, a Hilbert transform based EEG amplitude and a correlation coefficient method were compared.

Visual dysfunction and computational sleep depth changes in obstructive sleep apnea syndrome.

The aims of this study are to clarify whether patients with obstructive sleep apnea syndrome (OSAS) have a decline in verbally or visually-based cognitive abilities and whether the possible decline is related to particular sleep depth changes. In addition, the effect of continuous positive airway pressure (CPAP) on the possible changes is investigated. Fifteen OSAS patients and 15 healthy controls joined two full-night polysomnographies, including a computational measure of deep sleep percentage (DS%) bilaterally from the frontal, central and occipital channels, and a neuropsychological assessment.

Compressed tracheal sound analysis in screening of sleep-disordered breathing.

Objective: To evaluate the suitability of compressed tracheal sound signal for screening sleep-disordered breathing.

Methods: Thirty-three consecutive patients underwent a polysomnography with a tracheal sound analysis. Nineteen patients were healthy except for the sleep complaint, 9 were hypertonic and 3 were hypertonic and had elevated cholesterol.

Reducing the effects of electrocardiographic artifacts on electro-oculography in automatic sleep analysis.

Removal of electrocardiographic (ECG) artifacts of QRS complexes from a single channel electroencephalography (EEG) and electro-oculography (EOG) can be problematic especially when no reference ECG signal is available. This study examined a simple estimation method excluding the possible QRS part of the EOG trace before spectrum estimation. The method was tested using a simple sleep classifier based on 0.

Development and comparison of four sleep spindle detection methods.

Objective: The objective of the present work was to develop and compare methods for automatic detection of bilateral sleep spindles.

Methods And Materials: All-night sleep electroencephalographic (EEG) recordings of 12 healthy subjects with a median age of 40 years were studied. The data contained 6043 visually scored bilateral spindles occurring in frontopolar or central brain location.

Systematic performance evaluation of a continuous-scale sleep depth measure.

In this article, systematic performance evaluation of a continuous-scale sleep depth measure will be discussed. Our main objective has been to select the adjustable analysis parameters such that the best possible correspondence between method output and standard visual sleep staging could be achieved. Sleep depth estimation was based on continuous monitoring of short-time EEG synchronization through the local mean frequency of the EEG.

Topographic differences in mean computational sleep depth between healthy controls and obstructive sleep apnoea patients.

In this work, topographic differences in computational sleep depth between healthy controls and obstructive sleep apnoea syndrome (OSAS) patients have been examined. Sleep depth estimation was based on continuous monitoring of the mean frequency of the EEG. During the experiments, all-night sleep EEG recordings of carefully age and gender matched sets of 16 healthy controls and 16 OSAS patients were compared on six electrode locations (Fp1-M2, Fp2-M1, C3-M2, C4-M1, O1-M2, and O2-M1).

Apnea patients show a frontopolar inter-hemispheric spindle frequency difference.

Sleep apnea syndrome is known to disturb sleep. The purpose of the present work was to study spindle frequency in apnea patients. All-night sleep EEG recordings of 15 apnea patients and 15 control subjects with median ages of 47 and 46 years, respectively, were studied.

Computer program for automated sleep depth estimation.

In this article, we present a new implementation of an amplitude-independent method for continuous-scale sleep depth estimation. Having been implemented as an add-on analysis module under commercially available biosignal recording and analysis software, it can be easily applied in clinical routine. The software gives the user full freedom to change all the analysis parameters inside theoretical limits.

Determination of dominant simulated spindle frequency with different methods.

Accurate analysis of EEG sleep spindle frequency is challenging. The frequency content of true sleep spindles is not known. Therefore, simulated spindle activity was studied in the present work.

Anteroposterior difference in EEG sleep depth measure is reduced in apnea patients.

In the present work, mean frequencies of FFT amplitude spectra from six EEG derivations were used to provide a frontopolar, a central and an occipital sleep depth measure. Parameters quantifying the anteroposterior differences in these three sleep depth measures during the night were also developed. The method was applied to analysis of 30 all-night recordings from 15 healthy control subjects and 15 apnea patients.

Automatic detection of spiking events in EMFi sheet during sleep.

In this paper we present a new method for detection of spiking events caused by the increased respiratory resistance (IRR) from ballistocardiographic (BCG) data recorded with EMFi sheet. Spiking is a phenomenon where BCG wave complexes increase in amplitude during IRR. In this study data from six patients with a total of 1503 visually scored spiking events were studied.

Automated frequency analysis of synchronous and diffuse sleep spindles.

Background: Sleep spindles have different properties in different localizations in the cortex.

Objectives: First main objective was to develop an amplitude-independent multi-channel spindle detection method. Secondly the method was applied to study the anteroposterior frequency differences of pure synchronous (visible bilaterally, either frontopolarly or centrally) and diffuse (visible bilaterally both frontopolarly and centrally) sleep spindles.

Automatic quantification of light sleep shows differences between apnea patients and healthy subjects.

A fully automatic method to quantify sleep depth during the night was developed in the present work. The method was tested using 20 all-night recordings from 10 healthy control subjects and 10 sleep apnea patients. The results showed statistically significant differences in sleep depth between control subjects and sleep apnea patients.

Occurrence of periodic sleep spindles within and across non-REM sleep episodes.

Sleep spindles have been reported to occur both as single events and periodically in sequences. However, there is no systematic description about the occurrence of spindles in sequences in relation to time of night. The aim of the present study was to examine the temporal occurrence of periodic sleep spindles during the night.

Spindle frequency remains slow in sleep apnea patients throughout the night.

Background: Our previous data suggested that in normal sleep the frequency of individual sleep spindles would be related to sleep depth and possibly to sleep pressure. Thus far spindle frequency patterns in patients with sleep disorders have not been studied. It would be expected that the spindle frequencies might be affected by sleep fragmentation disturbing the sleep process.