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Author Middleton, B.; Arendt, J.; Stone, BM
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 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.
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Publisher Wiley Place of Publication Editor
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Call Number IDA @ john @ Serial 1098
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Author Crowley, S.J.; Suh, C.; Molina, T.A.; Fogg, L.F.; Sharkey, K.M.; Carskadon, M.A.
Title Estimating the dim light melatonin onset of adolescents within a 6-h sampling window: the impact of sampling rate and threshold method Type Journal Article
Year 2015 Publication Sleep Medicine Abbreviated Journal Sleep Medicine
Volume 20 Issue Pages 59-66
Keywords Human Health
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ISSN 1389-9457 ISBN Medium
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Call Number LoNNe @ kyba @ Serial 1324
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Author WDS Killgore
Title Lighting the Way to Better Sleep and Health Type Journal Article
Year 2016 Publication Journal of Sleep Disorders: Treatment and Care Abbreviated Journal J Sleep Disor: Treat Care
Volume 05 Issue 01 Pages
Keywords Health; Editorial
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ISSN 2325-9639 ISBN Medium
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Call Number LoNNe @ kyba @ Serial 1442
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Author Pereira, É.F.; Louzada, F.M.; Moreno, C.R.C.
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 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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ISSN 1446-9235 ISBN Medium
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Call Number LoNNe @ kyba @ Serial 1482
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Author Wang, H.-B.; Whittaker, D.S.; Truong, D.; Mulji, A.K.; Ghiani, C.A.; Loh, D.H.; Colwell, C.S.
Title Blue light therapy improves circadian dysfunction as well as motor symptoms in two mouse models of Huntington's disease Type Journal Article
Year 2017 Publication Neurobiology of Sleep and Circadian Rhythms Abbreviated Journal Neurobiology of Sleep and Circadian Rhythms
Volume 2 Issue Pages 39-52
Keywords animals; Human Health
Abstract Patients with Huntington's disease (HD) exhibit movement disorders, psychiatric disturbance and cognitive impairments as the disease progresses. Abnormal sleep/wake cycles are common among HD patients with reports of delayed sleep onset, fatigue during the day, and a delayed pattern of melatonin secretion all of which suggest circadian dysfunction. Mouse models of HD confirm disrupted circadian rhythms with pathophysiology found in the central circadian clock (suprachiasmatic nucleus). Importantly, circadian dysfunction manifests early in disease, even before the classic motor symptoms, in both patients and mouse models. Therefore, we hypothesize that the circadian dysfunction may interact with the disease pathology and exacerbate the HD symptoms. If correct, early intervention may benefit patients and delay disease progression. One test of this hypothesis is to determine whether light therapy designed to strengthen this intrinsic timing system can delay the disease progression in mouse models. Therefore, we determined the impact of blue wavelength-enriched light on two HD models: the BACHD and Q175 mice. Both models received 6 hours of blue-light at the beginning of their daily light cycle for 3 months. After treatment, both genotypes showed improvements in their locomotor activity rhythm without significant change to their sleep behavior. Critically, treated mice of both lines exhibited improved motor performance compared to untreated controls. Focusing on the Q175 genotype, we sought to determine whether the treatment altered signaling pathways in brain regions known to be impacted by HD using NanoString gene expression assays. We found that the expression of several HD relevant markers was altered in the striatum and cortex of the treated mice. Our study demonstrates that strengthening the circadian system can delay the progression of HD in pre-clinical models. This work suggests that lighting conditions should be considered when managing treatment of HD and other neurodegenerative disorders.
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ISSN 2451-9944 ISBN Medium
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Notes (down) Approved no
Call Number LoNNe @ kyba @ Serial 1626
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