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Author Hasler, B.P. url  doi
openurl 
  Title Commentary on Bedroom Light Exposure at Night and the Incidence of Depressive Symptoms: A Longitudinal Study of the HEIJOKYO Cohort (Obayashi et al) Type Journal Article
  Year 2018 Publication (up) American Journal of Epidemiology Abbreviated Journal  
  Volume 187 Issue 3 Pages 435-438  
  Keywords Commentary; Human Health  
  Abstract In modern society, we are increasingly disconnected from natural light/dark cycles and beset by round-the-clock exposure to artificial light. Light has powerful effects on physical and mental health, in part via the circadian system, and thus the timing of light exposure dictates whether it is helpful or harmful. In their compelling paper, Obayashi and colleagues offer evidence that light at night can prospectively predict an elevated incidence of depressive symptoms in older adults. Strengths of the study include the longitudinal design and direct, objective assessment of light levels, as well as accounting for multiple plausible confounders during analyses. Follow-up studies should address the study's limitations, including reliance on a global self-report of sleep quality and a two-night assessment of light exposure that may not reliably represent typical light exposure. In addition, experimental studies including physiological circadian measures will be necessary to determine if the light effects on depression are mediated through the circadian system or are so-called “direct” effects of light. In any case, these exciting findings could inform novel new approaches to preventing depressive disorders in older adults.  
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  ISSN 0002-9262 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number LoNNe @ kyba @ Serial 1716  
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Author Obayashi, K.; Saeki, K.; Kurumatani, N. url  doi
openurl 
  Title Obayashi et al. Respond to “Light at Night Predicts Depression—What Next?” Type Journal Article
  Year 2018 Publication (up) American Journal of Epidemiology Abbreviated Journal  
  Volume 187 Issue 3 Pages 439-440  
  Keywords Commentary; Human Health  
  Abstract Our research includes some strengths and limitations. The most important strength is objective measurement of light at night (LAN) intensity using a bedside light meter. Most previous studies evaluating the association between LAN and health outcomes have assessed indoor LAN levels using a self-reported questionnaire or outdoor LAN levels using satellite data; however, self-reported indoor LAN levels has not yet been validated with objective measurement and outdoor LAN levels are surrogates for an individual LAN exposure. The second strength of our study includes its longitudinal design using multivariable methods to adjust for confounders, which indicated LAN exposure may be a cause of the incidence of depressive symptoms. Indeed, the depressive score evaluated by questionnaires may be above or below the cut-off value over the short term; therefore, a long-term study considering such unstable outcomes should be conducted. In the current study, LAN exposure was measured for only two nights; thus, an amplitude of LAN intensity has been focused. However, multiple measurements over time in the future study would allow an analysis of fluctuations in LAN exposure, which might be important for circadian physiology.  
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  ISSN 0002-9262 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number LoNNe @ kyba @ Serial 1717  
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Author Obayashi, K.; Saeki, K.; Kurumatani, N. url  doi
openurl 
  Title Bedroom Light Exposure at Night and the Incidence of Depressive Symptoms: A Longitudinal Study of the HEIJO-KYO Cohort Type Journal Article
  Year 2018 Publication (up) American Journal of Epidemiology Abbreviated Journal Am J Epidemiol  
  Volume 187 Issue 3 Pages 427-434  
  Keywords Human Health; Mental Health; indoor light; geriatrics; Sleep; Sleep Disorders  
  Abstract Previous studies have indicated that minimal exposure to light at night (LAN) increases depression risk, even at 5 lux, in nocturnal and diurnal mammals. Although such low-level LAN may affect human circadian physiology, the association between exposure to LAN and depressive symptoms remains uncertain. In the present study, bedroom light intensity was measured objectively, and depressive symptoms were assessed, during 2010-2014 in Nara, Japan. Of 863 participants (mean age = 71.5 years) who did not have depressive symptoms at baseline, 73 participants reported development of depressive symptoms during follow-up (median, 24 months). Compared with the “dark” group (average of <5 lux; n = 710), the LAN group (average of >/=5 lux; n = 153) exhibited a significantly higher depression risk (hazard ratio = 1.89; 95% CI: 1.13, 3.14), according to a Cox proportional hazards model adjusting for age, sex, body mass index, and economic status. Further, the significance remained in a multivariable model adjusting for hypertension, diabetes, and sleep parameters (hazard ratio = 1.72; 95% CI: 1.03, 2.89). Sensitivity analyses using bedroom light data with a cutoff value of >/=10 lux suggested consistent results. In conclusion, these results indicated that exposure to LAN in home settings was independently associated with subsequent depression risk in an elderly general population.  
  Address Department of Community Health and Epidemiology, Nara Medical University School of Medicine, 840 Shijocho, Kashiharashi, Nara 634-8521, Japan; e-mail: obayashi(at)naramed-u.ac.jp  
  Corporate Author Thesis  
  Publisher Oxford Academic Place of Publication Editor  
  Language English Summary Language English Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0002-9262 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:28992236 Approved no  
  Call Number IDA @ john @ Serial 1815  
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Author Ashkenazi, I. E.; Reinberg, A,; Bicakova-Rocher, A.; Ticher, A. url  openurl
  Title The genetic background of individual variations of circadian-rhythm periods in healthy human adults. Type Journal Article
  Year 1993 Publication (up) 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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  Notes Approved no  
  Call Number LoNNe @ schroer @ Serial 582  
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Author Ruger, M.; Gordijn, M.C.M.; Beersma, D.G.M.; de Vries, B.; Daan, S. url  doi
openurl 
  Title Time-of-day-dependent effects of bright light exposure on human psychophysiology: comparison of daytime and nighttime exposure Type Journal Article
  Year 2006 Publication (up) American Journal of Physiology. Regulatory, Integrative and Comparative Physiology Abbreviated Journal Am J Physiol Regul Integr Comp Physiol  
  Volume 290 Issue 5 Pages R1413-20  
  Keywords Human Health; Adult; Body Temperature/*physiology; Circadian Rhythm/*physiology; Fatigue/*physiopathology; Heart Rate/*physiology; Humans; Hydrocortisone/*blood; *Light; Sleep Stages/*physiology  
  Abstract Bright light can influence human psychophysiology instantaneously by inducing endocrine (suppression of melatonin, increasing cortisol levels), other physiological changes (enhancement of core body temperature), and psychological changes (reduction of sleepiness, increase of alertness). Its broad range of action is reflected in the wide field of applications, ranging from optimizing a work environment to treating depressed patients. For optimally applying bright light and understanding its mechanism, it is crucial to know whether its effects depend on the time of day. In this paper, we report the effects of bright light given at two different times of day on psychological and physiological parameters. Twenty-four subjects participated in two experiments (n = 12 each). All subjects were nonsmoking, healthy young males (18-30 yr). In both experiments, subjects were exposed to either bright light (5,000 lux) or dim light <10 lux (control condition) either between 12:00 P.M. and 4:00 P.M. (experiment A) or between midnight and 4:00 A.M. (experiment B). Hourly measurements included salivary cortisol concentrations, electrocardiogram, sleepiness (Karolinska Sleepiness Scale), fatigue, and energy ratings (Visual Analog Scale). Core body temperature was measured continuously throughout the experiments. Bright light had a time-dependent effect on heart rate and core body temperature; i.e., bright light exposure at night, but not in daytime, increased heart rate and enhanced core body temperature. It had no significant effect at all on cortisol. The effect of bright light on the psychological variables was time independent, since nighttime and daytime bright light reduced sleepiness and fatigue significantly and similarly.  
  Address Department of Chronobiology, University of Groningen, The Netherlands. Melanie.Rueger@med.nyu.edu  
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  Series Volume Series Issue Edition  
  ISSN 0363-6119 ISBN Medium  
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  Notes PMID:16373441 Approved no  
  Call Number LoNNe @ kagoburian @ Serial 801  
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