Sleep, vigilance, and thermosensitivity

The regulation of sleep and wakefulness is well modeled with two underlying processes: a circadian and a homeostatic one. So far, the parameters and mechanisms of additional sleep-permissive and wake-promoting conditions have been largely overlooked. The present overview focuses on one of these conditions: the effect of skin temperature on the onset and maintenance of sleep, and alertness. Skin temperature is quite well suited to provide the brain with information on sleep-permissive and wake-promoting conditions because it changes with most if not all of them. Skin temperature changes with environmental heat and cold, but also with posture, environmental light, danger, nutritional status, pain, and stress. Its effect on the brain may thus moderate the efficacy by which the clock and homeostat manage to initiate or maintain sleep or wakefulness. The review provides a brief overview of the neuroanatomical pathways and physiological mechanisms by which skin temperature can affect the regulation of sleep and vigilance. In addition, current pitfalls and possibilities of practical applications for sleep enhancement are discussed, including the recent finding of impaired thermal comfort perception in insomniacs

Recharge yourself: Recharge interventions during festival-induced sleep loss

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Erratum: Measuring dissimilarity between respiratory effort signals based on uniform scaling for sleep staging (2014 Physiol. Meas. 35 2539)

Due to a typesetting error, the following sentence was incorrectly displayed in the final manuscript as ‘The deployment of respiratory effort dissimilarity with several consecutive breaths (as measured by a uniform scaling distance) to characterize the regulation of breathing within wscore between two deep sleep epochs.’ The correct sentence should read ‘The deployment of respiratory effort dissimilarity with several consecutive breaths (as measured by a uniform scaling distance) to characterize the regulation of breathing within different sleep stages was investigated. On average, we observe the lowest dissimilarity score between two deep sleep epochs.

Towards unobtrusive automated sleep stage classification:polysomnography using electrodes on the face

\u3cp\u3eAlthough sleep stage annotation (SSA) is historically known from clinical practice and typically performed by a certified expert on the basis of visual examination of polysomnography (PSG) signals. Automatic SSA has emerged as a tool to assist sleep experts and to accelerate the analysis of PSG data. New advances in signal processing and sensor technology start to enable the application of SSA in home solutions as well. In today's busy lives, sleep plays a central role and good quality sleep helps us to deal with the stress of everyday life. Being able to enhance sleep quality thus is a major opportunity to help people in reducing the influence of stress on their live, health and wellbeing. The advent of consumer products aimed at enhancing the sleep experience has propelled the need for home sleep monitoring and inducing solutions which can i) provide automatic SSA using sensors that interfere minimally with the sleep process and ii) provide sleep stage information in real-time in order to be suitable for closed-loop sleep inducing solutions. In this paper, we examine two possible alternatives for unobtrusive sleep monitoring. The first one uses respiratory, cardiac and wrist actigraphy signals while the second one relies on Facial PSG electrodes positioned on the facial area which allow for unobtrusive and comfortable sensors arrangements.\u3c/p\u3

Maleic hydrazide interaction with soil clay surfaces.

The binding mechanism of the herbicide maleic hydrazide (MH) to mineral soil clay surfaces has been studied by adsorption isotherms at different pH, X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FT-IR). The results showed different mechanisms depending of the surface characteristics of the minerals. For hydroxylated (variable charge) surfaces such as lepidocrocite and sepiolite, the adsorption of MH occurred at external surfaces whereas for phyllosilicates of negative permanent charge, such as montmorillonite, MH penetred also in the interlamellar spaces, as shown by XRD results. FT-IR spectra of MH-mineral complexes showed that MH was bonded to surface hydroxyl on lepidocrocite and sepiolite and to exchangeable cation, directly or through water-bridge, on montmorillonite by C=0 groups of the herbicide molecule.Peer Reviewe

Erratum: Measuring dissimilarity between respiratory effort signals based on uniform scaling for sleep staging (2014 Physiol. Meas. 35 2539)

Due to a typesetting error, the following sentence was incorrectly displayed in the final manuscript as ‘The deployment of respiratory effort dissimilarity with several consecutive breaths (as measured by a uniform scaling distance) to characterize the regulation of breathing within wscore between two deep sleep epochs.’ The correct sentence should read ‘The deployment of respiratory effort dissimilarity with several consecutive breaths (as measured by a uniform scaling distance) to characterize the regulation of breathing within different sleep stages was investigated. On average, we observe the lowest dissimilarity score between two deep sleep epochs.

Sleep EEG characteristics associated with sleep onset misperception

Study objective\u3cbr/\u3eTo study sleep EEG characteristics associated with misperception of Sleep Onset Latency (SOL).\u3cbr/\u3e\u3cbr/\u3eMethods\u3cbr/\u3eData analysis was based on secondary analysis of standard in-lab polysomnographic recordings in 20 elderly people with insomnia and 21 elderly good sleepers. Parameters indicating sleep fragmentation, such as number of awakenings, wake after sleep onset (WASO) and percentage of NREM1 were extracted from the polsysomnogram, as well as spectral power, microarousals and sleep spindle index. The correlation between these parameters during the first sleep cycle and the amount of misperceived sleep was assessed in the insomnia group. Additionally, we made a model of the minimum duration that a sleep fragment at sleep onset should have in order to be perceived as sleep, and we fitted this model to subjective SOLs of both subject groups.\u3cbr/\u3e\u3cbr/\u3eResults\u3cbr/\u3eMisperception of SOL was associated with increased percentage of NREM1 and more WASO during sleep cycle 1. For insomnia subjects, the best fit of modelled SOL with subjective SOL was found when assuming that sleep fragments shorter than 30 min at sleep onset were perceived as wake. The model indicated that healthy subjects are less sensitive to sleep interruptions and perceive fragments of 10 min or longer as sleep.\u3cbr/\u3e\u3cbr/\u3eConclusions\u3cbr/\u3eOur findings suggest that sleep onset misperception is related to sleep fragmentation at the beginning of the night. Moreover, we show that people with insomnia needed a longer duration of continuous sleep for the perception as such compared to controls. Further expanding the model could provide more detailed information about the underlying mechanisms of sleep misperception