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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 Choi, S. J., Park, H. R. & Joo, E. Y.
Title Effects of Light on Daytime Sleep in 12 Hours Night Shift Workers: A Field Study Type Journal Article
Year 2019 Publication Korean Sleep Research Society Abbreviated Journal
Volume 16 Issue 1 Pages 26-35
Keywords Human Health; Sleep
Abstract Objectives: Night shift workers suffer from sleep and daytime disturbances due to circadian misalignment. To investigate the role of environmental light in daytime sleep following 12 h-night shift work. Methods: we enrolled 12 h-shift female nurses working at one university-affiliated hospital (n=10, mean age 26.6 years, shift work duration 3.8 years). This is a cross-over study to compare sleep between under light exposure (30 lux) and in the dark (<5 lux) following 12 h-night duty. Two sessions of experiments were underwent and the interval between sessions was about a month. Psychomotor vigilance test (PVT) had performed on awakening from sleep at each session and sleep-wake pattern had been monitored by actigraphy throughout the study period. Daytime sleep was also compared with night sleep of age-and gender matched daytime workers (n=10). Results: Sleep parameters and PVT scores were not different between two light conditions. Activities during sleep seemed to be more abundant under 30 lux condition than in the dark, which was not significant. Compared to night sleep, daytime sleep of shift workers was different in terms of rapid eye movement (REM) sleep. Three shift workers showed sleep onset REM sleep and first REM sleep period was the longest during daytime sleep. Conclusions: Unexpectedly, daytime sleep of 12 h night shift workers was well-maintained regardless of light exposure. Early occurrence of REM sleep and shorter sleep latency during daytime sleep suggest that shift workers meet with misalignment of circadian rhythm as well as increased homeostatic sleep pressure drive.
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Publisher Place of Publication Editor
Language Korean Summary Language Original Title
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Call Number IDA @ intern @ Serial 2635
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Author Woods, H. C., & Scott, H.
Title Merging the Biological and Cognitive Processes of Sleep and Screens Type Journal Article
Year 2019 Publication Current Sleep Medicine Reports Abbreviated Journal
Volume 5 Issue 3 Pages 150-155
Keywords Human Health
Abstract Purpose of Review

Screens are a permanent feature of life today and we have reached an interesting juncture with different research agendas investigating the biological and cognitive aspects of screen use separately. This review argues that it is timely and indeed essential that we bring together these research areas to fully understand both positive and negative aspects of screen use.

Recent Findings

More recent work is starting to take a more cohesive approach to understanding how device use pre-bedtime can impact our sleep by including both light and content in their experimental protocols which is a welcome development leading to a more nuanced understanding of both biological and cognitive processes.

Summary

We call for an open and collaborative approach to gain momentum in this direction of acknowledging both biological and cognitive factors enabling us to understand the relative impacts of both whilst using screens with regard to both light and content.
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Notes Approved no
Call Number IDA @ intern @ Serial 2640
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Author Chang, A.-M.; Scheer, F.A.J.L.; Czeisler, C.A.; Aeschbach, D.
Title Direct effects of light on alertness, vigilance, and the waking electroencephalogram in humans depend on prior light history Type Journal Article
Year 2013 Publication Sleep Abbreviated Journal Sleep
Volume 36 Issue 8 Pages 1239-1246
Keywords Arousal/*radiation effects; Attention/radiation effects; Cross-Over Studies; *Electroencephalography; Female; Humans; *Light; Male; Melatonin/blood/physiology; Psychomotor Performance/radiation effects; Reaction Time; Wakefulness/*radiation effects; Young Adult; Light history; alertness and performance; light exposure
Abstract STUDY OBJECTIVES: Light can induce an acute alerting response in humans; however, it is unknown whether the magnitude of this response is simply a function of the absolute illuminance of the light itself, or whether it depends on illuminance history preceding the stimulus. Here, we compared the effects of illuminance history on the alerting response to a subsequent light stimulus. DESIGN: A randomized, crossover design was used to compare the effect of two illuminance histories (1 lux vs. 90 lux) on the alerting response to a 6.5-h 90-lux light stimulus during the biological night. SETTING: Intensive Physiologic Monitoring Unit, Brigham and Women's Hospital, Boston, MA. PARTICIPANTS: Fourteen healthy young adults (6 F; 23.5 +/- 2.9 years). INTERVENTIONS: Participants were administered two 6.5-h light exposures (LE) of 90 lux during the biological night. For 3 days prior to each LE, participants were exposed to either 1 lux or 90 lux during the wake episode. MEASUREMENTS AND RESULTS: The alerting response to light was assessed using subjective sleepiness ratings, lapses of attention, and reaction times as measured with an auditory psychomotor vigilance task, as well as power density in the delta/theta range of the waking EEG. The alerting response to light was greater and lasted longer when the LE followed exposure to 1 lux compared to 90 lux light. CONCLUSION: The magnitude and duration of the alerting effect of light at night depends on the illuminance history and appears to be subject to sensitization and adaptation.
Address Division of Sleep Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA. amchang@rics.bwh.harvard.edu
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Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN (up) 0161-8105 ISBN Medium
Area Expedition Conference
Notes PMID:23904684; PMCID:PMC3700721 Approved no
Call Number IDA @ john @ Serial 145
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Author Kessel, L.; Siganos, G.; Jorgensen, T.; Larsen, M.
Title Sleep disturbances are related to decreased transmission of blue light to the retina caused by lens yellowing Type Journal Article
Year 2011 Publication Sleep Abbreviated Journal Sleep
Volume 34 Issue 9 Pages 1215-1219
Keywords Adult; Age Factors; Aging/*pathology/physiology; Circadian Rhythm/physiology; Cross-Sectional Studies; Female; Fluorometry; Humans; Lens, Crystalline/*pathology/physiopathology; *Light; Male; Middle Aged; Retina/*physiopathology; Risk Factors; *Scattering, Radiation; Sleep Disorders/*etiology; Circadian rhythm; cataract; melanopsin; sleep; blue light
Abstract STUDY OBJECTIVES: Sleep pattern and circadian rhythms are regulated via the retinohypothalamic tract in response to stimulation of a subset of retinal ganglion cells, predominantly by blue light (450-490 nm). With age, the transmission of blue light to the retina is reduced because of the aging process of the human lens, and this may impair the photoentrainment of circadian rhythm leading to sleep disorders. The aim of the study was to examine the association between lens aging and sleep disorders. DESIGN: Cross-sectional population based study. SETTING: The study was performed at the Research Center for Prevention and Health, Glostrup Hospital, Denmark and at the Department of Ophthalmology, Herlev Hospital, Denmark. PARTICIPANTS: An age- and sex-stratified sample of 970 persons aged 30 to 60 years of age drawn from a sample randomly selected from the background population. INTERVENTIONS: Not applicable. MEASUREMENTS AND RESULTS: Sleep disturbances were evaluated by a combination of questionnaire and the use of prescription sleeping medication. Lens aging (transmission and yellowing) was measured objectively by lens autofluorometry. The risk of sleep disturbances was significantly increased when the transmission of blue light to the retina was low, even after correction for the effect of age and other confounding factors such as smoking habits, diabetes mellitus, gender, and the risk of ischemic heart disease (P < 0.0001). CONCLUSIONS: Filtration of blue light by the aging lens was significantly associated with an increased risk of sleep disturbances. We propose that this is a result of disturbance of photoentrainment of circadian rhythms.
Address Department of Ophthalmology, Glostrup Hospital, University of Copenhagen, Denmark. line.kessel@dadlnet.dk
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Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN (up) 0161-8105 ISBN Medium
Area Expedition Conference
Notes PMID:21886359; PMCID:PMC3157663 Approved no
Call Number IDA @ john @ Serial 344
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