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Author (up) Ashkenazi, I. E.; Reinberg, A,; Bicakova-Rocher, A.; Ticher, A.
Title The genetic background of individual variations of circadian-rhythm periods in healthy human adults. Type Journal Article
Year 1993 Publication American Journal of Human Genetics Abbreviated Journal
Volume 52 Issue 6 Pages 1250–1259
Keywords Human Health; Adult; Body Temperature; Bronchi; Bronchi: physiology; Circadian Rhythm; Circadian Rhythm: genetics; Female; Genetic Variation; Hand; Hand: physiology; Heart Rate; Humans; Male; Middle Aged; Sex Factors; Sleep
Abstract As a group phenomenon, human variables exhibit a rhythm with a period (tau) equal to 24 h. However, healthy human adults may differ from one another with regard to the persistence of the 24-h periods of a set of variables' rhythms within a given individual. Such an internal desynchronization (or individual circadian dyschronism) was documented during isolation experiments without time cues, both in the present study involving 78 male shift workers and in 20 males and 19 females living in a natural setting. Circadian rhythms of sleep-wake cycles, oral temperature, grip strength of both hands, and heart rate were recorded, and power-spectra analyses of individual time series of about 15 days were used to quantify the rhythm period of each variable. The period of the sleep-wake cycle seldom differed from 24 h, while rhythm periods of the other variables exhibited a trimodal distribution (tau = 24 h, tau > 24 h, tau < 24 h). Among the temperature rhythm periods which were either < 24 h or > 24 h, none was detected between 23.2 and 24 h or between 24 and 24.8 h. Furthermore, the deviations from the 24-h period were predominantly grouped in multiples of +/- 0.8 h. Similar results were obtained when the rhythm periods of hand grip strength were analyzed (for each hand separately). In addition, the distribution of grip strength rhythm periods of the left hand exhibited a gender-related difference. These results suggested the presence of genetically controlled variability. Consequently, the distribution pattern of the periods was analyzed to elucidate its compatibility with a genetic control consisting of either a two-allele system, a multiple-allele system, or a polygenic system. The analysis resulted in structuring a model which integrates the function of a constitutive (essential) gene which produces the exact 24-h period (the Dian domain) with a set of (inducible) polygenes, the alleles of which, contribute identical time entities to the period. The time entities which affected the rhythm periods of the variables examined were in the magnitude of +/- 0.8 h. Such an assembly of genes may create periods ranging from 20 to 28 h (the Circadian domain). The model was termed by us “The Dian-Circadian Model.” This model can also be used to explain the beat phenomena in biological rhythms, the presence of 7-d and 30-d periods, and interindividual differences in sensitivity of rhythm characteristics (phase shifts, synchronization, etc.) to external (and environmental) factors.
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Call Number LoNNe @ schroer @ Serial 582
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Author (up) Atkinson, G.; Davenne, D.
Title Relationships between sleep, physical activity and human health Type Journal Article
Year 2007 Publication Physiology & Behavior Abbreviated Journal Physiol Behav
Volume 90 Issue 2-3 Pages 229-235
Keywords Human Health; Activity Cycles/*physiology; Animals; Body Temperature/physiology; Exercise/*physiology; Health; Humans; Motor Activity/physiology; Pineal Gland/physiology; Sleep/*physiology; Wakefulness/physiology
Abstract Although sleep and exercise may seem to be mediated by completely different physiological mechanisms, there is growing evidence for clinically important relationships between these two behaviors. It is known that passive body heating facilitates the nocturnal sleep of healthy elderly people with insomnia. This finding supports the hypothesis that changes in body temperature trigger somnogenic brain areas to initiate sleep. Nevertheless, little is known about how the core and distal thermoregulatory responses to exercise fit into this hypothesis. Such knowledge could also help in reducing sleep problems associated with nocturnal shiftwork. It is difficult to incorporate physical activity into a shiftworker's lifestyle, since it is already disrupted in terms of family commitments and eating habits. A multi-research strategy is needed to identify what the optimal amounts and timing of physical activity are for reducing shiftwork-related sleep problems. The relationships between sleep, exercise and diet are also important, given the recently reported associations between short sleep length and obesity. The cardiovascular safety of exercise timing should also be considered, since recent data suggest that the reactivity of blood pressure to a change in general physical activity is highest during the morning. This time is associated with an increased risk in general of a sudden cardiac event, but more research work is needed to separate the influences of light, posture and exercise per se on the haemodynamic responses to sleep and physical activity following sleep taken at night and during the day as a nap.
Address Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Henry Cotton Campus, Webster Street, Liverpool L3 2ET, UK. G.Atkinson@ljmu.ac.uk
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ISSN 0031-9384 ISBN Medium
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Notes PMID:17067643; PMCID:PMC2782301 Approved no
Call Number LoNNe @ kagoburian @ Serial 717
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Author (up) Boivin, D.B.; Duffy, J.F.; Kronauer, R.E.; Czeisler, C.A.
Title Dose-response relationships for resetting of human circadian clock by light Type Journal Article
Year 1996 Publication Nature Abbreviated Journal Nature
Volume 379 Issue 6565 Pages 540-542
Keywords Human Health; Adult; Body Temperature; Circadian Rhythm/*radiation effects; Dose-Response Relationship, Radiation; Humans; *Light; Male; NASA Discipline Number 18-10; NASA Discipline Regulatory Physiology; NASA Program Space Physiology and Countermeasures; Non-NASA Center
Abstract Since the first report in unicells, studies across diverse species have demonstrated that light is a powerful synchronizer which resets, in an intensity-dependent manner, endogenous circadian pacemakers. Although it is recognized that bright light (approximately 7,000 to 13,000 lux) is an effective circadian synchronizer in humans, it is widely believed that the human circadian pacemaker is insensitive to ordinary indoor illumination (approximately 50-300 lux). It has been proposed that the relationship between the resetting effect of light and its intensity follows a compressive nonlinear function, such that exposure to lower illuminances still exerts a robust effect. We therefore undertook a series of experiments which support this hypothesis and report here that light of even relatively low intensity (approximately 180 lux) significantly phase-shifts the human circadian pacemaker. Our results clearly demonstrate that humans are much more sensitive to light than initially suspected and support the conclusion that they are not qualitatively different from other mammals in their mechanism of circadian entrainment.
Address Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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ISSN 0028-0836 ISBN Medium
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Notes PMID:8596632 Approved no
Call Number LoNNe @ kagoburian @ Serial 722
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Author (up) Borniger, J.C.; Maurya, S.K.; Periasamy, M.; Nelson, R.J.
Title Acute dim light at night increases body mass, alters metabolism, and shifts core body temperature circadian rhythms Type Journal Article
Year 2014 Publication Chronobiology International Abbreviated Journal Chronobiol Int
Volume 31 Issue 8 Pages 917-925
Keywords Animals; Body temperature; calorimetry; circadian; light at night; metabolism
Abstract The circadian system is primarily entrained by the ambient light environment and is fundamentally linked to metabolism. Mounting evidence suggests a causal relationship among aberrant light exposure, shift work, and metabolic disease. Previous research has demonstrated deleterious metabolic phenotypes elicited by chronic (>4 weeks) exposure to dim light at night (DLAN) ( approximately 5 lux). However, the metabolic effects of short-term (<2 weeks) exposure to DLAN are unspecified. We hypothesized that metabolic alterations would arise in response to just 2 weeks of DLAN. Specifically, we predicted that mice exposed to dim light would gain more body mass, alter whole body metabolism, and display altered body temperature (Tb) and activity rhythms compared to mice maintained in dark nights. Our data largely support these predictions; DLAN mice gained significantly more mass, reduced whole body energy expenditure, increased carbohydrate over fat oxidation, and altered temperature circadian rhythms. Importantly, these alterations occurred despite similar activity locomotor levels (and rhythms) and total food intake between groups. Peripheral clocks are potently entrained by body temperature rhythms, and the deregulation of body temperature we observed may contribute to metabolic problems due to “internal desynchrony” between the central circadian oscillator and temperature sensitive peripheral clocks. We conclude that even relatively short-term exposure to low levels of nighttime light can influence metabolism to increase mass gain.
Address Department of Neuroscience and
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ISSN 0742-0528 ISBN Medium
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Notes PMID:24933325 Approved no
Call Number LoNNe @ kagoburian @ Serial 846
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Author (up) Cajochen, C.; Munch, M.; Kobialka, S.; Krauchi, K.; Steiner, R.; Oelhafen, P.; Orgul, S.; Wirz-Justice, A.
Title High sensitivity of human melatonin, alertness, thermoregulation, and heart rate to short wavelength light Type Journal Article
Year 2005 Publication The Journal of Clinical Endocrinology and Metabolism Abbreviated Journal J Clin Endocrinol Metab
Volume 90 Issue 3 Pages 1311-1316
Keywords Human Health; Adult; Body Temperature Regulation/physiology/*radiation effects; Circadian Rhythm/physiology/radiation effects; Color; Heart Rate/physiology/*radiation effects; Humans; *Light; Male; Melatonin/*metabolism; Retinal Cone Photoreceptor Cells/physiology; Sleep Stages/physiology/radiation effects; Wakefulness/physiology/*radiation effects
Abstract Light can elicit acute physiological and alerting responses in humans, the magnitude of which depends on the timing, intensity, and duration of light exposure. Here, we report that the alerting response of light as well as its effects on thermoregulation and heart rate are also wavelength dependent. Exposure to 2 h of monochromatic light at 460 nm in the late evening induced a significantly greater melatonin suppression than occurred with 550-nm monochromatic light, concomitant with a significantly greater alerting response and increased core body temperature and heart rate ( approximately 2.8 x 10(13) photons/cm(2)/sec for each light treatment). Light diminished the distal-proximal skin temperature gradient, a measure of the degree of vasoconstriction, independent of wavelength. Nonclassical ocular photoreceptors with peak sensitivity around 460 nm have been found to regulate circadian rhythm function as measured by melatonin suppression and phase shifting. Our findings-that the sensitivity of the human alerting response to light and its thermoregulatory sequelae are blue-shifted relative to the three-cone visual photopic system-indicate an additional role for these novel photoreceptors in modifying human alertness, thermophysiology, and heart rate.
Address Centre for Chronobiology, Psychiatric University Clinic, Wilhelm Kleinstr. 27, CH-4025 Basel, Switzerland. christian.cajochen@pukbasel.ch
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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-972X ISBN Medium
Area Expedition Conference
Notes PMID:15585546 Approved no
Call Number LoNNe @ kagoburian @ Serial 728
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