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Author Middleton, B.; Arendt, J.; Stone, BM url  openurl
  Title Human circadian rhythms in constant dim light (8 lux) with knowledge of clock time Type Journal Article
  Year 1996 Publication Journal of Sleep Research Abbreviated Journal J. Sleep Res.  
  Volume 5 Issue 2 Pages 69-76  
  Keywords Human Health; circadian rhythm; light/dark cycle; melatonin; entrainment; melatonin levels; 6-sulphatoxymelatonin  
  Abstract (up) The light/dark (L/D) cycle is a major synchronizer of human circadian rhythms. In the absence of a strong L/D cycle, synchrony with 24 hours can nevertheless be maintained in a socially structured environment, as shown in Polar regions (Broadway et al. 1987) and by some blind subjects (Czeisler et al. 1995a). The relative contribution of other time cues to entrainment in dim light has not been fully explored. The present study investigated the behaviour of melatonin (assessed as 6-sulphatoxymelatonin); rectal temperature; activity and sleep (actigraphy and logs) in constant dim light (L/ L) with access to a digital clock. 6 normal healthy males were maintained as a group in partial temporal isolation with attenuated sound and ambient temperature for 21 days. All 6 subjects showed free-running periodicity for 6-sulphatoxymelatonin and 5/6 subjects for temperature, activity and sleep offset. The average period (tau) was 24.26 +/- 0.049, substantially shorter than in previous experiments with a self selected L/D cycle but similar to a recent study conducted in very dim light. One subject maintained a rigid sleep/wake cycle throughout whilst his 6-sulphatoxymelatonin rhythm free-ran. Total sleep time, from actigraph data, did not change but sleep efficiency decreased during the experiment. The subjects did not show group synchronization. These results confirm previous data indicating the importance of the L/D cycle in human entrainment and underline the lesser role of social cues and knowledge of clock time. This particular approach will permit the administration of timed medication to sighted humans under free-running conditions.  
  Address  
  Corporate Author Thesis  
  Publisher Wiley Place of Publication Editor  
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  Notes Approved no  
  Call Number IDA @ john @ Serial 1098  
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Author Pereira, É.F.; Louzada, F.M.; Moreno, C.R.C. url  doi
openurl 
  Title Not all adolescents are sleep deprived: A study of rural populations: Sleep duration in rural populations Type Journal Article
  Year 2010 Publication Sleep and Biological Rhythms Abbreviated Journal  
  Volume 8 Issue 4 Pages 267-273  
  Keywords Human Health; Sleep  
  Abstract (up) The objective of this study was to investigate the role of environmental factors in sleep duration among adolescents living in rural areas. A total of 1140 students (569 males), aged 10–19 years, and attending two schools in rural regions in southern Brazil, completed a questionnaire about their sleep habits. Demographic data were also obtained. Prevalence ratios (PR) were estimated for the cases of more than 9 h of sleep on weekdays. Sleep duration in adolescents with and without electric lighting at home was analyzed. Average sleep duration at night was 9.63 (1.64) h on school-going days and 10.14 (2.42) h on weekends. The prevalence of adolescents sleeping for more than 9 h at night on school-going days was 58.3%. Older adolescents showed a tendency to delay their sleep onset times, which is associated with a reduction of sleep duration. Adolescents without electric lighting at home slept longer on school-going days (P < 0.001) and on weekends (P= 0.013) when compared to those with electric lighting at home. From multivariate analysis, age (P < 0.001), school schedule (P= 0.007) and work (0.042) were factors affecting sleep duration. In contrast to the data previously reported for urban populations, we found a high prevalence of adolescents sleeping for more than 9 h on school nights. Data on populations living in less industrialized regions reinforce the idea that technological advances are associated with the negative impact of sleep phase delay in adolescents.  
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  Series Volume Series Issue Edition  
  ISSN 1446-9235 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number LoNNe @ kyba @ Serial 1482  
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Author Escobar, C.; Salgado-Delgado, R.; Gonzalez-Guerra, E.; Tapia Osorio, A.; Angeles-Castellanos, M.; Buijs, R.M. url  doi
openurl 
  Title Circadian disruption leads to loss of homeostasis and disease Type Journal Article
  Year 2011 Publication Sleep Disorders Abbreviated Journal Sleep Disord  
  Volume 2011 Issue Pages 964510  
  Keywords Human Health  
  Abstract (up) The relevance of a synchronized temporal order for adaptation and homeostasis is discussed in this review. We present evidence suggesting that an altered temporal order between the biological clock and external temporal signals leads to disease. Evidence mainly based on a rodent model of “night work” using forced activity during the sleep phase suggests that altered activity and feeding schedules, out of phase from the light/dark cycle, may be the main cause for the loss of circadian synchrony and disease. It is proposed that by avoiding food intake during sleep hours the circadian misalignment and adverse consequences can be prevented. This review does not attempt to present a thorough revision of the literature, but instead it aims to highlight the association between circadian disruption and disease with special emphasis on the contribution of feeding schedules in circadian synchrony.  
  Address Departamento de Anatomia, Facultad de Medicina, Universidad Nacional Autonoma de Mexico, 04360 Mexico City, DF, Mexico  
  Corporate Author Thesis  
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  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2090-3553 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:23471148; PMCID:PMC3581131 Approved no  
  Call Number LoNNe @ kagoburian @ Serial 745  
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Author Smith, M.R.; Eastman, C.I. url  doi
openurl 
  Title Shift work: health, performance and safety problems, traditional countermeasures, and innovative management strategies to reduce circadian misalignment Type Journal Article
  Year 2012 Publication Nature and Science of Sleep Abbreviated Journal Nat Sci Sleep  
  Volume 4 Issue Pages 111-132  
  Keywords bright light; circadian rhythms; melatonin; night work; phase-shifting; sleep  
  Abstract (up) There are three mechanisms that may contribute to the health, performance, and safety problems associated with night-shift work: (1) circadian misalignment between the internal circadian clock and activities such as work, sleep, and eating, (2) chronic, partial sleep deprivation, and (3) melatonin suppression by light at night. The typical countermeasures, such as caffeine, naps, and melatonin (for its sleep-promoting effect), along with education about sleep and circadian rhythms, are the components of most fatigue risk-management plans. We contend that these, while better than nothing, are not enough because they do not address the underlying cause of the problems, which is circadian misalignment. We explain how to reset (phase-shift) the circadian clock to partially align with the night-work, day-sleep schedule, and thus reduce circadian misalignment while preserving sleep and functioning on days off. This involves controlling light and dark using outdoor light exposure, sunglasses, sleep in the dark, and a little bright light during night work. We present a diagram of a sleep-and-light schedule to reduce circadian misalignment in permanent night work, or a rotation between evenings and nights, and give practical advice on how to implement this type of plan.  
  Address Biological Rhythms Research Laboratory, Rush University Medical Center, Chicago, IL, USA  
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  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1179-1608 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:23620685; PMCID:PMC3630978 Approved no  
  Call Number IDA @ john @ Serial 149  
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