Pulse Oximetry at the Wrist During Sleep: Performance, Challenges and Perspectives.

The state-of-the-art non-invasive measurement of peripheral oxygen saturation (SpO2) during sleep is mainly based on pulse oximetry at the fingertip. Although this approach is noninvasive, it can still be obtrusive and cumbersome to apply, in particular for ambulatory monitoring over several nights.We developed a wrist-worn reflectance pulse oximetry device which can be embedded in a watch, making it less obtrusive and easy to apply.

Personalized Sleep Spindle Detection in Whole Night Polysomnography.

The present study proposes a new personalized sleep spindle detection algorithm, suggesting the importance of an individualized approach. We identify an optimal set of features that characterize the spindle and exploit a support vector machine to distinguish between spindle and nonspindle patterns. The algorithm is assessed on the open source DREAMS database, that contains only selected part of the polysomnography, and on whole night polysomnography recordings from the SPASH database.

Automated sleep scoring: A review of the latest approaches.

Clinical sleep scoring involves a tedious visual review of overnight polysomnograms by a human expert, according to official standards. It could appear then a suitable task for modern artificial intelligence algorithms. Indeed, machine learning algorithms have been applied to sleep scoring for many years.

Stroke causes a transient imbalance of interhemispheric information flow in EEG during non-REM sleep.

Objective: Large-scale connectivity, especially interhemispheric connections, plays a crucial role for recovery after stroke. Here we used methods from information theory to characterize interhemispheric information flow in wake- and sleep-EEG after cerebral ischemia.

Methods: 34 patients with unilateral ischemic stroke were included.

K-band Doppler radar for contact-less overnight sleep marker assessment: a pilot validation study.

An estimated 45 million persons in Europe are annually subjected to sleep-wake disorders. State-of-the-art polysomnography provides sophisticated insights into sleep (patho)physiology. A drawback of the method, however, is the obtrusive setting dependent on a clinical-based sleep laboratory with high operational costs.

Subjective perception of sleepiness in a driving simulator is different from that in the Maintenance of Wakefulness Test.

Objective: To test whether sleep-deprived, healthy subjects who do not always signal spontaneously perceived sleepiness (SPS) before falling asleep during the Maintenance of Wakefulness Test (MWT) would do so in a driving simulator.

Methods: Twenty-four healthy subjects (20-26 years old) underwent a MWT for 40 min and a driving simulator test for 1 h, before and after one night of sleep deprivation. Standard electroencephalography, electrooculography, submental electromyography, and face videography were recorded simultaneously to score wakefulness and sleep.

Word encoding during sleep is suggested by correlations between word-evoked up-states and post-sleep semantic priming.

To test whether humans can encode words during sleep we played everyday words to men while they were napping and assessed priming from sleep-played words following waking. Words were presented during non-rapid eye movement (NREM) sleep. Priming was assessed using a semantic and a perceptual priming test.

Epileptic seizures as condensed sleep: an analysis of network dynamics from electroencephalogram signals.

Both deepening sleep and evolving epileptic seizures are associated with increasing slow-wave activity. Larger-scale functional networks derived from electroencephalogram indicate that in both transitions dramatic changes of communication between brain areas occur. During seizures these changes seem to be 'condensed', because they evolve more rapidly than during deepening sleep.

Sleep stage II contributes to the consolidation of declarative memories.

Various studies suggest that non-rapid eye movement (NREM) sleep, especially slow-wave sleep (SWS), is vital to the consolidation of declarative memories. However, sleep stage 2 (S2), which is the other NREM sleep stage besides SWS, has gained only little attention. The current study investigated whether S2 during an afternoon nap contributes to the consolidation of declarative memories.

EEG correlation and power during maintenance of wakefulness test after sleep-deprivation.

Objectives: To investigate whether there are any objective EEG characteristics that change significantly between specific time periods during maintenance of wakefulness test (MWT) and whether such changes are associated with the ability to appropriately communicate sleepiness.

Methods: After a night of total sleep deprivation, 12 healthy young subjects underwent a MWT whilst being instructed to communicate the experience of subjective sleepiness by pressing a button. EEG analysis consisted of average relative power and correlation between EEG signals.

Selective REM sleep deprivation in narcolepsy.

Narcolepsy is characterized by excessive daytime sleepiness and rapid eye movement (REM) sleep abnormalities, including cataplexy. The aim of this study was to assess REM sleep pressure and homeostasis in narcolepsy. Six patients with narcolepsy and six healthy controls underwent a REM sleep deprivation protocol, including one habituation, one baseline, two deprivation nights (D1, D2) and one recovery night.

Sleepiness is not always perceived before falling asleep in healthy, sleep-deprived subjects.

Objective: To test whether subjects spontaneously signal sleepiness before falling asleep under monotonous conditions.

Methods: Twenty-eight healthy students were deprived of sleep for one night and then underwent a "maintenance-of-wakefulness test" (MWT) consisting of four 40-min trials. They were told to give a signal as soon as they felt sleepy and to try to stay awake as long as possible.

Effects of sleep fragmentation on the arousability to resistive loading in NREM and REM sleep in normal men.

Study Objective: In healthy subjects, arousability to inspiratory resistive loading is greater during rapid eye movement (REM) sleep compared with non-REM (NREM) sleep but is poorest in REM sleep in patients with sleep apnea. We therefore examined the hypothesis that sleep fragmentation impairs arousability, especially from REM sleep.

Design: Two blocks of 3 polysomnographies (separated by at least 1 week) were performed randomly.

Evolution of sleep and sleep EEG after hemispheric stroke.

The evolution of subjective sleep and sleep electroencephalogram (EEG) after hemispheric stroke have been rarely studied and the relationship of sleep variables to stroke outcome is essentially unknown. We studied 27 patients with first hemispheric ischaemic stroke and no sleep apnoea in the acute (1-8 days), subacute (9-35 days), and chronic phase (5-24 months) after stroke. Clinical assessment included estimated sleep time per 24 h (EST) and Epworth sleepiness score (ESS) before stroke, as well as EST, ESS and clinical outcome after stroke.

Visual and spectral analysis of sleep EEG in acute hemispheric stroke.

Background: Reports on the effects of focal hemispheric damage on sleep EEG are rare and contradictory.

Patients And Methods: Twenty patients (mean age +/- SD 53 +/- 14 years) with a first acute hemispheric stroke and no sleep apnea were studied. Stroke severity [National Institute of Health Stroke Scale (NIHSS)], volume (diffusion-weighted brain MRI), and short-term outcome (Rankin score) were assessed.