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"Rhythm."
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Circadian misalignment increases cardiovascular disease risk factors in humans
Shift work is a risk factor for hypertension, inflammation, and cardiovascular disease. This increased risk cannot be fully explained by classic risk factors. One of the key features of shift workers is that their behavioral and environmental cycles are typically misaligned relative to their endogenous circadian system. However, there is little information on the impact of acute circadian misalignment on cardiovascular disease risk in humans. Here we show—by using two 8-d laboratory protocols—that short-term circadian misalignment (12-h inverted behavioral and environmental cycles for three days) adversely affects cardiovascular risk factors in healthy adults. Circadian misalignment increased 24-h systolic blood pressure (SBP) and diastolic blood pressure (DBP) by 3.0 mmHg and 1.5 mmHg, respectively. These results were primarily explained by an increase in blood pressure during sleep opportunities (SBP, +5.6 mmHg; DBP, +1.9 mmHg) and, to a lesser extent, by raised blood pressure during wake periods (SBP, +1.6 mmHg; DBP, +1.4 mmHg). Circadian misalignment decreased wake cardiac vagal modulation by 8–15%, as determined by heart rate variability analysis, and decreased 24-h urinary epinephrine excretion rate by 7%, without a significant effect on 24-h urinary norepinephrine excretion rate. Circadian misalignment increased 24-h serum interleukin-6, C-reactive protein, resistin, and tumor necrosis factor-α levels by 3–29%. We demonstrate that circadian misalignment per se increases blood pressure and inflammatory markers. Our findings may help explain why shift work increases hypertension, inflammation, and cardiovascular disease risk.
Journal Article
Perceptual Image of Sound: A Gestalt Approach
In primitive and early superior cultures, different elements (such as human beings, events, natural phenomena, and objects) were grouped into the same rhythmic category only because they had similar forms. This rhythm—which can be reproduced in a song or on a drum—also characterizes the individual animal, human being, or object because of their unique shape, form, or movement. According to Benveniste’s proposal, the original meaning of “rhythm” (ῥυθμός) was the perception of a “peculiar way of flowing,” or a “spatial configuration defined by the distinctive arrangement and proportion of elements” (my translation). This definition is very similar to that of form/Gestalt/structure/system, that is, a whole that is not the mere sum of its parts but is something more and something new, determined by the relationships among the components. Gestalt psychology originated from the perception of sound and was then applied to the perception of speech, audio-vision, and music. Audio-vision is an illusion, created by the fusion of two signals that come together in a new configuration, a new rhythm, a new form in the subject’s perception. In music, the perception of Gestalt/rhythmic structures is shaped by the changing characteristics of the sound field, which are influenced by the physical data, the musical structure, and the listener’s experiences and expectations. Consequently, music and perception are engaged in a cyclical process of repetition/redundancy/assimilation and change/variation/accommodation that continually reshapes our sound field perceptual organization.
Journal Article
Music in time : phenomenology, perception, performance
Music exists in time. All musicians know this fundamental truth?but what does it actually mean? Thirteen scholars probe the temporality of music from a great variety of perspectives, in response to challenges that Christopher F. Hasty, Walter Naumburg Professor of Music at Harvard University, laid out in his groundbreaking 'Meter as Rhythm'. 00The essays included here bridge the conventional divides between theory, history, ethnomusicology, aesthetics, performance practice, cognitive psychology, and dance studies. In these investigations, music emerges as an art form that has an important lesson to teach. Not only can music be understood as sounds shaped in time but?more radically?as time shaped in sounds.
Book
Circadian rhythms, sleep, and metabolism
The discovery of the genetic basis for circadian rhythms has expanded our knowledge of the temporal organization of behavior and physiology. The observations that the circadian gene network is present in most living organisms from eubacteria to humans, that most cells and tissues express autonomous clocks, and that disruption of clock genes results in metabolic dysregulation have revealed interactions between metabolism and circadian rhythms at neural, molecular, and cellular levels. A major challenge remains in understanding the interplay between brain and peripheral clocks and in determining how these interactions promote energy homeostasis across the sleep-wake cycle. In this Review, we evaluate how investigation of molecular timing may create new opportunities to understand and develop therapies for obesity and diabetes.
Journal Article
Human circadian variations
Circadian rhythms, present in most phyla across life, are biological oscillations occurring on a daily cycle. Since the discovery of their molecular foundations in model organisms, many inputs that modify this tightly controlled system in humans have been identified. Polygenic variations and environmental factors influence each person's circadian rhythm, contributing to the trait known as chronotype, which manifests as the degree of morning or evening preference in an individual. Despite normal variation in chronotype, much of society operates on a \"one size fits all\" schedule that can be difficult to adjust to, especially for certain individuals whose endogenous circadian phase is extremely advanced or delayed. This is a public health concern, as phase misalignment in humans is associated with a number of adverse health outcomes. Additionally, modern technology (such as electric lights and computer, tablet, and phone screens that emit blue light) and lifestyles (such as shift or irregular work schedules) are disrupting circadian consistency in an increasing number of people. Though medical and lifestyle interventions can alleviate some of these issues, growing research on endogenous circadian variability and sensitivity suggests that broader social changes may be necessary to minimize the impact of circadian misalignment on health.
Journal Article
Delayed sleep-onset and biological age: late sleep-onset is associated with shorter telomere length
We evaluated the relationship between leukocyte telomere length (LTL) and sleep duration, insomnia symptoms, and circadian rhythm, to test whether sleep and chronobiological dysregulations are associated with cellular aging.
Data from the Netherlands Study of Depression and Anxiety (N = 2,936) were used at two waves 6 years apart, to measure LTL. Telomeres shorten during the life span and are important biomarkers for cellular aging. LTL was assessed by qualitative polymerase chain reaction and converted into base pair number. Sleep parameters were: sleep duration and insomnia symptoms from the Insomnia Rating Scale. Circadian rhythm variables were: indication of Delayed Sleep Phase Syndrome (DSPS), mid-sleep corrected for sleep debt on free days (MSFsc), sleep-onset time, and self-reported chronotype, from the Munich Chronotype Questionnaire. Generalized estimating equations analyzed the associations between LTL, sleep, and chronobiological factors, adjusted for baseline age, sex, North European ancestry, and additionally for current smoking, depression severity, obesity, and childhood trauma.
Indicators of delayed circadian rhythm showed a strong and consistent effect on LTL, after adjustment for sociodemographic and health indicators. Late MSFsc (B = -49.9, p = .004), late sleep-onset time (B = -32.4, p = .001), indication of DSPS (B = -73.8, p = .036), and moderately late chronotype in adulthood (B = -71.6, p = .003) were associated with significantly shorter LTL across both waves; whereas sleep duration and insomnia symptoms were not. Extremely early chronotype showed significantly less LTL shortening than intermediate chronotype (B = 161.40, p = .037). No predictors showed accelerated LTL attrition over 6 years.
Individuals with delayed circadian rhythm have significantly shorter LTL, but not faster LTL attrition rates.
Journal Article