scholarly journals Conscious experiences and high-density EEG patterns predicting subjective sleep depth

2021 ◽  
Author(s):  
Aurélie M. Stephan ◽  
Sandro Lecci ◽  
Jacinthe Cataldi ◽  
Francesca Siclari
Keyword(s):  
High Density ◽  
Subjective Sleep ◽  
Sleep Depth

scholarly journals The determinants of the subjective perception of sleep: insights from a high-density EEG study with serial awakenings

2021 ◽  
Author(s):  
Aurelie M Stephan ◽  
Sandro Lecci ◽  
Jacinthe Cataldi ◽  
Francesca Siclari
Keyword(s):  
Eye Movement ◽  
Rem Sleep ◽  
High Frequency ◽  
Nrem Sleep ◽  
High Density ◽  
Subjective Perception ◽  
Rapid Eye Movement ◽  
Eeg Activity ◽  
Subjective Sleep ◽  
Sleep Depth

What determines the feeling of being asleep? Standard sleep recordings only incompletely reflect subjective aspects of sleep and some individuals with so-called sleep misperception frequently feel awake although sleep recordings indicate clear-cut sleep. Here we performed 787 awakenings in 20 good sleepers and 10 individuals with severe sleep misperception to interview them about their subjective sleep depth while they underwent high-density EEG sleep recordings (256-channels). Surprisingly, in good sleepers, sleep was subjectively lightest in the first two hours of Non-rapid eye movement (NREM) sleep, generally considered the ′deepest′ sleep, and deepest in rapid eye movement (REM) sleep. Compared to good sleepers, sleep misperceptors felt more frequently awake during sleep, reported overall lighter REM sleep and had more thought-like conscious experiences. In both groups, subjective sleep depth positively correlated with dream-like features of conscious experiences. At the EEG level, spatially widespread high-frequency power was inversely related to subjective sleep depth in NREM sleep in both groups and in REM sleep in misperceptors. Taken together, these findings challenge the widely held notion that ′deep′ (slow wave) sleep best accounts for feeling soundly asleep. Instead, they suggest that subjective sleep depth is inversely related to a neurophysiological process that predominates in NREM sleep early in the night, becomes quiescent in REM sleep and is reflected in high-frequency EEG-activity. In sleep misperceptors, this neurophysiological process is more active and spatially widespread, and abnormally persists into REM sleep. Thus, it is not the presence of ′sleep rhythms′ but rather the absence of ′wake-like′ EEG activity that predicts the feeling of being deeply asleep. These findings will help identify the neuromodulatory systems involved in subjective sleep depth and are therefore relevant for future studies aiming to improve subjective sleep quality.

035 Activating the concept of “relaxation” during sleep using relaxation-related words

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A15-A16
Author(s):  
Jonas Beck ◽  
Erna Loretz ◽  
Björn Rasch
Keyword(s):  
Sleep Quality ◽  
Slow Wave ◽  
Nrem Sleep ◽  
Sleep Cycle ◽  
Relaxation Techniques ◽  
Semantic Meaning ◽  
Subjective Sleep Quality ◽  
Subjective Sleep ◽  
Sleep Depth ◽  
Sleep Physiology

Abstract Introduction Cognitive processes (e.g., rumination, perception of an unfamiliar sleeping environment, relaxation techniques) alter our sleep, but the underlying mechanisms are still unknown. Theories of embodied or grounded cognition assume that semantic meaning is stored in multimodal neuronal networks. We therefore assume that cognitive concepts are closely linked to related bodily functions. We propose that mental processes are active to a greater or lesser extent during sleep and that this degree of activation affects our sleep depth. Methods We examined this notion by activating the concept of “relaxation” during sleep using relaxation-related words in 50 healthy participants. After an adaption night, subjects slept in the sleep laboratory for two experimental nights according to a within-subject cross-over design. During one experimental night, relaxing words (e.g., “sea”, “relax”) were presented to promote sleep depth. During the other experimental night, control words were presented (e.g., “produce”, “materials”). As the amount of SWS peaks within the first sleep cycle, words were presented during NREM sleep starting with the second sleep cycle (at the latest 120 min after sleep onset). In addition, a mood and a subjective sleep quality questionnaire was conducted. Results In support of our hypothesis, playing relaxing words during non-rapid eye movement sleep extended the time spent in slow-wave sleep during the period, when words were presented. Furthermore, power in the slow-wave activity band was increased several seconds after the cue for relaxing compared with control words. The increased sleep depth by means of relaxing words was accompanied by a reduced interhemispheric asymmetry of SWA and slow-wave density in the during-cueing period. The changes observed in objective sleep translated to the subjective level with an increase in subjective sleep quality and alertness ratings. Conclusion The present study showed that the semantic meaning of words presented during NREM sleep is capable of affecting sleep physiology, SWS maintenance and the subjective evaluation of sleep quality. Our results support the notion that the activation of mental concepts during sleep can influence sleep depth and provide a basis for interventions using targeted activations to promote sleep depth and sleep quality to foster well-being and health. Support (if any):

Planar defects in ordered (Ga,In)P

1988 ◽  
Vol 46 ◽  
pp. 902-903
Author(s):  
S. McKernan ◽  
C. B. Carter ◽  
D. Bour ◽  
J. R. Shealy
Keyword(s):  
Electron Diffraction ◽  
Vapor Phase ◽  
Growth Direction ◽  
High Density ◽  
Ordered Structure ◽  
Planar Defects ◽  
Diffraction Patterns ◽  
Ternary Semiconductors ◽  
Anion Species ◽  
Metallic Vapor

The growth of ternary III-V semiconductors by organo-metallic vapor phase epitaxy (OMVPE) is widely practiced. It has been generally assumed that the resulting structure is the same as that of the corresponding binary semiconductors, but with the two different cation or anion species randomly distributed on their appropriate sublattice sites. Recently several different ternary semiconductors including AlxGa1-xAs, Gaxln-1-xAs and Gaxln1-xP1-6 have been observed in ordered states. A common feature of these ordered compounds is that they contain a relatively high density of defects. This is evident in electron diffraction patterns from these materials where streaks, which are typically parallel to the growth direction, are associated with the extra reflections arising from the ordering. However, where the (Ga,ln)P epilayer is reasonably well ordered the streaking is extremely faint, and the intensity of the ordered spot at 1/2(111) is much greater than that at 1/2(111). In these cases it is possible to image relatively clearly many of the defects found in the ordered structure.

Quantitative defect studies in semiconductor TEM samples prepared by low angle ion milling

1995 ◽  
Vol 53 ◽  
pp. 512-513
Author(s):  
L. Mulestagno ◽  
J.C. Holzer ◽  
P. Fraundorf
Keyword(s):  
Sample Preparation ◽  
Milling Time ◽  
High Density ◽  
Low Density ◽  
Ion Milling ◽  
High Quality ◽  
Variable Angle ◽  
Major Disadvantage ◽  
Induced Defects

Due to the wealth of information, both analytical and structural that can be obtained from it TEM always has been a favorite tool for the analysis of process-induced defects in semiconductor wafers. The only major disadvantage has always been, that the volume under study in the TEM is relatively small, making it difficult to locate low density defects, and sample preparation is a somewhat lengthy procedure. This problem has been somewhat alleviated by the availability of efficient low angle milling.Using a PIPS® variable angle ion -mill, manufactured by Gatan, we have been consistently obtaining planar specimens with a high quality thin area in excess of 5 × 104 μm2 in about half an hour (milling time), which has made it possible to locate defects at lower densities, or, for defects of relatively high density, obtain information which is statistically more significant (table 1).

Using the scanning electron microscope for failure analysis of high density magnetic media

1987 ◽  
Vol 45 ◽  
pp. 392-393
Author(s):  
Evelyn R. Ackerman ◽  
Gary D. Burnett
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Failure Analysis ◽  
High Density ◽  
Magnetic Media ◽  
Specific Data ◽  
Retrieval Systems ◽  
Operating Environments ◽  
The Media ◽  
Scanning Electron

Advancements in state of the art high density Head/Disk retrieval systems has increased the demand for sophisticated failure analysis methods. From 1968 to 1974 the emphasis was on the number of tracks per inch. (TPI) ranging from 100 to 400 as summarized in Table 1. This emphasis shifted with the increase in densities to include the number of bits per inch (BPI). A bit is formed by magnetizing the Fe203 particles of the media in one direction and allowing magnetic heads to recognize specific data patterns. From 1977 to 1986 the tracks per inch increased from 470 to 1400 corresponding to an increase from 6300 to 10,800 bits per inch respectively. Due to the reduction in the bit and track sizes, build and operating environments of systems have become critical factors in media reliability.Using the Ferrofluid pattern developing technique, the scanning electron microscope can be a valuable diagnostic tool in the examination of failure sites on disks.

Triglyceride to high density lipoprotein cholesterol ratio, total cholesterol to high density lipoprotein cholesterol ratio and low ankle brachial index in an elderly population

VASA ◽  
2014 ◽  
Vol 43 (3) ◽  
pp. 189-197 ◽  
Author(s):  
Yiqiang Zhan ◽  
Jinming Yu ◽  
Rongjing Ding ◽  
Yihong Sun ◽  
Dayi Hu
Keyword(s):  
High Density Lipoprotein ◽  
Total Cholesterol ◽  
High Density Lipoprotein Cholesterol ◽  
Ankle Brachial Index ◽  
Density Lipoprotein ◽  
High Density ◽  
Lipoprotein Cholesterol ◽  
Lipid Lowering ◽  
Cholesterol Ratio ◽  
Potential Biomarker

Background: The associations of triglyceride (TG) to high-density lipoprotein cholesterol ratio (HDL‑C) and total cholesterol (TC) to HDL‑C ratio and low ankle brachial index (ABI) were seldom investigated. Patients and methods: A population based cross-sectional survey was conducted and 2982 participants 60 years and over were recruited. TG, TC, HDL‑C, and low-density lipoprotein cholesterol (LDL-C) were assessed in all participants. Low ABI was defined as ABI ≤ 0.9 in either leg. Multiple logistic regression models were applied to study the association between TG/HDL‑C ratio, TC/HDL‑C ratio and low ABI. Results: The TG/HDL‑C ratios for those with ABI > 0.9 and ABI ≤ 0.9 were 1.28 ± 1.20 and 1.48 ± 1.13 (P < 0.0001), while the TC/HDL‑C ratios were 3.96 ± 1.09 and 4.32 ± 1.15 (P < 0.0001), respectively. After adjusting for age, gender, body mass index, obesity, current drinking, physical activity, hypertension, diabetes, lipid-lowering drugs, and cardiovascular disease history, the odds ratios (ORs) with 95 % confidence intervals (CIs) of low ABI for TG/HDL‑C ratio and TC/HDL‑C ratio were 1.10 (0.96, 1.26) and 1.34 (1.14, 1.59) in non-smokers. When TC was further adjusted, the ORs (95 % CIs) were 1.40 (0.79, 2.52) and 1.53 (1.21, 1.93) for TG/HDL‑C ratio and TC/HDL‑C ratio, respectively. Non-linear relationships were detected between TG/HDL‑C ratio and TC/HDL‑C ratio and low ABI in both smokers and non-smokers. Conclusions: TC/HDL‑C ratio was significantly associated with low ABI in non-smokers and the association was independent of TC, TG, HDL‑C, and LDL-C. TC/HDL‑C might be considered as a potential biomarker for early peripheral arterial disease screening.

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