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Author Wright, K.P.J.; Hull, J.T.; Czeisler, C.A.
Title Relationship between alertness, performance, and body temperature in humans Type Journal Article
Year 2002 Publication American Journal of Physiology. Regulatory, Integrative and Comparative Physiology Abbreviated Journal Am J Physiol Regul Integr Comp Physiol
Volume 283 Issue 6 Pages R1370-7
Keywords Human Health; Adult; Attention/*physiology; *Body Temperature; Circadian Rhythm/physiology; Cognition/*physiology; Female; Humans; Male; Memory/physiology; Reaction Time; Sleep/physiology; Time Factors; Wakefulness/physiology; NASA Discipline Regulatory Physiology; Non-NASA Center
Abstract Body temperature has been reported to influence human performance. Performance is reported to be better when body temperature is high/near its circadian peak and worse when body temperature is low/near its circadian minimum. We assessed whether this relationship between performance and body temperature reflects the regulation of both the internal biological timekeeping system and/or the influence of body temperature on performance independent of circadian phase. Fourteen subjects participated in a forced desynchrony protocol allowing assessment of the relationship between body temperature and performance while controlling for circadian phase and hours awake. Most neurobehavioral measures varied as a function of internal biological time and duration of wakefulness. A number of performance measures were better when body temperature was elevated, including working memory, subjective alertness, visual attention, and the slowest 10% of reaction times. These findings demonstrate that an increased body temperature, associated with and independent of internal biological time, is correlated with improved performance and alertness. These results support the hypothesis that body temperature modulates neurobehavioral function in humans.
Address Division of Sleep Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA. kenneth.wright@colorado.edu
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0363-6119 ISBN Medium
Area Expedition Conference
Notes PMID:12388468 Approved no
Call Number LoNNe @ kagoburian @ Serial (down) 835
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Author Santhi, N.; Thorne, H.C.; van der Veen, D.R.; Johnsen, S.; Mills, S.L.; Hommes, V.; Schlangen, L.J.M.; Archer, S.N.; Dijk, D.-J.
Title The spectral composition of evening light and individual differences in the suppression of melatonin and delay of sleep in humans Type Journal Article
Year 2012 Publication Journal of Pineal Research Abbreviated Journal J Pineal Res
Volume 53 Issue 1 Pages 47-59
Keywords Human Health; Adult; *Circadian Clocks; Cross-Sectional Studies; Electroencephalography; Female; Humans; Male; Melatonin/*metabolism; Photic Stimulation; *Photoperiod; Rod Opsins/*metabolism; *Sleep; *Sleep Disorders, Circadian Rhythm/etiology/metabolism/physiopathology; Time Factors
Abstract The effect of light on circadian rhythms and sleep is mediated by a multi-component photoreceptive system of rods, cones and melanopsin-expressing intrinsically photosensitive retinal ganglion cells. The intensity and spectral sensitivity characteristics of this system are to be fully determined. Whether the intensity and spectral composition of light exposure at home in the evening is such that it delays circadian rhythms and sleep also remains to be established. We monitored light exposure at home during 6-8wk and assessed light effects on sleep and circadian rhythms in the laboratory. Twenty-two women and men (23.1+/-4.7yr) participated in a six-way, cross-over design using polychromatic light conditions relevant to the light exposure at home, but with reduced, intermediate or enhanced efficacy with respect to the photopic and melanopsin systems. The evening rise of melatonin, sleepiness and EEG-assessed sleep onset varied significantly (P<0.01) across the light conditions, and these effects appeared to be largely mediated by the melanopsin, rather than the photopic system. Moreover, there were individual differences in the sensitivity to the disruptive effect of light on melatonin, which were robust against experimental manipulations (intra-class correlation=0.44). The data show that light at home in the evening affects circadian physiology and imply that the spectral composition of artificial light can be modified to minimize this disruptive effect on sleep and circadian rhythms. These findings have implications for our understanding of the contribution of artificial light exposure to sleep and circadian rhythm disorders such as delayed sleep phase disorder.
Address Surrey Sleep Research Centre, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK. n.santhi@surrey.ac.uk
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0742-3098 ISBN Medium
Area Expedition Conference
Notes PMID:22017511 Approved no
Call Number LoNNe @ kagoburian @ Serial (down) 802
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Author Kujanik, S.; Mikulecky, M.
Title Circadian and ultradian extrasystole rhythms in healthy individuals at elevated versus lowland altitudes Type Journal Article
Year 2010 Publication International Journal of Biometeorology Abbreviated Journal Int J Biometeorol
Volume 54 Issue 5 Pages 531-538
Keywords Human Health; Acclimatization/physiology; Aged; *Altitude; Anoxia/etiology; Cardiac Complexes, Premature/*physiopathology; Circadian Rhythm/*physiology; Electrocardiography, Ambulatory; Heart Rate/*physiology; Humans; Male; Middle Aged; Reference Values; Time Factors
Abstract We defined chronobiologic norms for supraventricular and ventricular single extrasystoles (SV and VE, respectively) in healthy older males in lowland areas. The study was extended to higher altitudes, where hypobaric hypoxia was expected to increase extrasystole frequency, while perhaps not changing rhythmicity. In healthy men (lowland n = 37, altitude n = 22), aged 49-72 years, mean numbers of SVs and VEs were counted over a 24-h period. Cosinor regression was used to test the 24-h rhythm and its 2nd-10th harmonics. The resulting approximating function for either extrasystole type includes its point, 95% confidence interval of the mean, and 95% tolerance for single measurement estimates. Separate hourly differences (delta) between altitude and lowland (n = 59) were also analysed. Hourly means were significantly higher in the mountains versus lowland, by +0.8 beats/h on average for SVs, and by +0.9 beats/h for VEs. A relatively rich chronogram for VEs in mountains versus lowland exists. Delta VEs clearly display a 24-h component and its 2nd, 3rd, 4th and 7th harmonics. This results in significantly higher accumulation of VEs around 8.00 a.m., 11.00 a.m. and 3.00 p.m. in the mountains. The increase in extrasystole occurrence in the mountains is probably caused by higher hypobaric hypoxia and resulting sympathetic drive. Healthy men at elevated altitudes show circadian and several ultradian rhythms of single VEs dependent on the hypoxia level. This new methodological approach--evaluating the differences between two locations using delta values--promises to provide deeper insight into the occurrence of premature beats.
Address Dept of Physiology, Faculty of Medicine, Pavol Jozef Safarik University, Trieda SNP 1, 040 66 Kosice, Slovak Republic. stefan.kujanik@upjs.sk
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0020-7128 ISBN Medium
Area Expedition Conference
Notes PMID:20195873 Approved no
Call Number LoNNe @ kagoburian @ Serial (down) 774
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Author Kovac, J.; Husse, J.; Oster, H.
Title A time to fast, a time to feast: the crosstalk between metabolism and the circadian clock Type Journal Article
Year 2009 Publication Molecules and Cells Abbreviated Journal Mol Cells
Volume 28 Issue 2 Pages 75-80
Keywords Human Health; Animals; Biological Clocks/*physiology; CLOCK Proteins/genetics/metabolism; Circadian Rhythm/*physiology; Energy Metabolism/*physiology; Gene Expression Regulation; Homeostasis; Humans; Period Circadian Proteins/genetics/metabolism; Time Factors
Abstract The cyclic environmental conditions brought about by the 24 h rotation of the earth have allowed the evolution of endogenous circadian clocks that control the temporal alignment of behaviour and physiology, including the uptake and processing of nutrients. Both metabolic and circadian regulatory systems are built upon a complex feedback network connecting centres of the central nervous system and different peripheral tissues. Emerging evidence suggests that circadian clock function is closely linked to metabolic homeostasis and that rhythm disruption can contribute to the development of metabolic disease. At the same time, metabolic processes feed back into the circadian clock, affecting clock gene expression and timing of behaviour. In this review, we summarize the experimental evidence for this bimodal interaction, with a focus on the molecular mechanisms mediating this exchange, and outline the implications for clock-based and metabolic diseases.
Address Circadian Rhythms Group, Max Planck Institute of Biophysical Chemistry, 37077, Gottingen, Germany
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1016-8478 ISBN Medium
Area Expedition Conference
Notes PMID:19714310 Approved no
Call Number LoNNe @ kagoburian @ Serial (down) 772
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Author Filipski, E.; Subramanian, P.; Carriere, J.; Guettier, C.; Barbason, H.; Levi, F.
Title Circadian disruption accelerates liver carcinogenesis in mice Type Journal Article
Year 2009 Publication Mutation Research Abbreviated Journal Mutat Res
Volume 680 Issue 1-2 Pages 95-105
Keywords Human Health; Animals; Alanine Transaminase/blood; Animals; Aspartate Aminotransferases/blood; Bile Duct Neoplasms/chemically induced/pathology; Bile Ducts, Intrahepatic/drug effects/pathology; Body Weight/drug effects; Carcinogens/administration & dosage/*toxicity; Carcinoma, Hepatocellular/chemically induced/pathology; Cholangiocarcinoma/chemically induced/pathology; Circadian Rhythm/*drug effects; Diethylnitrosamine/administration & dosage/*toxicity; Dose-Response Relationship, Drug; Injections, Intraperitoneal; Liver/drug effects/pathology; Liver Neoplasms/blood/*chemically induced/pathology; Male; Mice; Neoplasms, Multiple Primary/chemically induced/pathology; Sarcoma/chemically induced/pathology; Time Factors
Abstract BACKGROUND: The circadian timing system rhythmically controls behavior, physiology, cellular proliferation and xenobiotic metabolism over the 24-h period. The suprachiasmatic nuclei in the hypothalamus coordinate the molecular clocks in most mammalian cells through an array of circadian physiological rhythms including rest-activity, body temperature, feeding patterns and hormonal secretions. As a result, shift work that involves circadian disruption is probably carcinogenic in humans. In experimental models, chronic jet-lag (CJL) suppresses rest-activity and body temperature rhythms and accelerates growth of two transplantable tumors in mice. CJL also suppresses or significantly alters the expression rhythms of clock genes in liver and tumors. Circadian clock disruption from CJL downregulates p53 and upregulates c-Myc, thus favoring cellular proliferation. Here, we investigate the role of CJL as a tumor promoter in mice exposed to the hepatic carcinogen, diethylnitrosamine (DEN). METHODS: In experiment 1 (Exp 1), the dose-dependent carcinogenicity of chronic intraperitoneal (i.p.) administration of DEN was explored in mice. In Exp 2, mice received DEN at 10 mg/kg/day (cumulative dose: 243 mg/kg), then were randomized to remain in a photoperiodic regimen where 12 h of light alternates with 12 h of darkness (LD 12:12) or to be submitted to CJL (8-h advance of light onset every 2 days). Rest-activity and body temperature were monitored. Serum liver enzymes were determined repeatedly. Mice were sacrificed and examined for neoplastic lesions at 10 months. RESULTS: In Exp 1, DEN produced liver cancers in all the mice receiving 10 mg/kg/day. In Exp 2, mice on CJL had increased mean plasma levels of aspartate aminotransferase and more liver tumors as compared to LD mice at approximately 10 months (p = 0.005 and 0.028, respectively). The mean diameter of the largest liver tumor was twice as large in CJL vs LD mice (8.5 vs 4.4 mm, p = 0.027). In LD, a single histologic tumor type per liver was observed. In CJL, up to four different types were associated in the same liver (hepatocellular- or cholangio-carcinomas, sarcomas or mixed tumors). DEN itself markedly disrupted the circadian rhythms in rest-activity and body temperature in all the mice. DEN-induced disruption was prolonged for >or= 3 months by CJL exposure. CONCLUSIONS: The association of circadian disruption with chronic DEN exposure suggests that circadian clocks actively control the mechanisms of liver carcinogenesis in mice. Persistent circadian coordination may further be critical for slowing down and/or reverting cancer development after carcinogen exposure.
Address INSERM, U776 Rythmes Biologiques et Cancers, Hopital Paul Brousse, Villejuif F-94807, France
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0027-5107 ISBN Medium
Area Expedition Conference
Notes PMID:19833225 Approved no
Call Number LoNNe @ kagoburian @ Serial (down) 747
Permanent link to this record