| Records |
| Author |
Vetter, C.; Juda, M.; Lang, D.; Wojtysiak, A.; Roenneberg, T. |
| Title |
Blue-enriched office light competes with natural light as a zeitgeber |
Type |
Journal Article |
| Year |
2011 |
Publication |
Scandinavian Journal of Work, Environment & Health |
Abbreviated Journal |
Scand J Work Environ Health |
| Volume |
37 |
Issue |
5 |
Pages |
437-445 |
| Keywords |
*Circadian Rhythm; *Color; Humans; *Lighting; *Occupational Health; Sleep; Wakefulness; blue light; circadian disruption; Circadian rhythm; sleep |
| Abstract |
OBJECTIVES: Circadian regulation of human physiology and behavior (eg, body temperature or sleep-timing), depends on the “zeitgeber” light that synchronizes them to the 24-hour day. This study investigated the effect of changing light temperature at the workplace from 4000 Kelvin (K) to 8000 K on sleep-wake and activity-rest behavior. METHODS: An experimental group (N=27) that experienced the light change was compared with a non-intervention group (N=27) that remained in the 4000 K environment throughout the 5-week study period (14 January to 17 February). Sleep logs and actimetry continuously assessed sleep-wake behavior and activity patterns. RESULTS: Over the study period, the timing of sleep and activity on free days steadily advanced parallel to the seasonal progression of sunrise in the non-intervention group. In contrast, the temporal pattern of sleep and activity in the experimental group remained associated with the constant onset of work. CONCLUSION: The results suggest that artificial blue-enriched light competes with natural light as a zeitgeber. While subjects working under the warmer light (4000 K) appear to entrain (or synchronize) to natural dawn, the subjects who were exposed to blue-enriched (8000 K) light appear to entrain to office hours. The results confirm that light is the dominant zeitgeber for the human clock and that its efficacy depends on spectral composition. The results also indicate that blue-enriched artificial light is a potent zeitgeber that has to be used with diligence. |
| Address |
Institute for Medical Psychology, Centre of Chronobiology, Ludwig-Maximilians-Universitat, Munich, Germany |
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English |
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Edition |
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| ISSN |
0355-3140 |
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| Notes |
PMID:21246176 |
Approved |
no |
| Call Number |
IDA @ john @ |
Serial |
350 |
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| Author |
Zukauskas, A.; Vaicekauskas, R.; Vitta, P. |
| Title |
Optimization of solid-state lamps for photobiologically friendly mesopic lighting |
Type |
Journal Article |
| Year |
2012 |
Publication |
Applied Optics |
Abbreviated Journal |
Appl Opt |
| Volume |
51 |
Issue |
35 |
Pages |
8423-8432 |
| Keywords |
Lighting Systems; Circadian Rhythm; Color; Equipment Design; Humans; Light; *Lighting; Melatonin/metabolism; Photobiology/*methods; Semiconductors; Time Factors; Vision, Ocular |
| Abstract |
The circadian and visual-performance-based mesopic systems of photometry were applied for the optimization of the spectral power distributions (SPDs) of the solid-state sources of light for low-illuminance lighting applications. At mesopic adaptation luminances typical of outdoor lighting (0.1-2 cd/m(2)), the optimal SPDs were obtained through the minimization of the mesopic circadian action factor, which is the ratio of the circadian efficacy of radiation to mesopic luminous efficacy of radiation. For correlated color temperatures below ~3000 K, the optimized dichromatic light-emitting diodes (LEDs) are shown to pose a lower circadian hazard than high-pressure sodium lamps and common warm white LEDs; also they are potentially more efficacious and have acceptable color rendition properties under mesopic conditions. |
| Address |
Institute of Applied Research, Vilnius University, Sauletekio al. 9-III, Vilnius LT-10222, Lithuania. arturas.zukauskas@ff.vu.lt |
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English |
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| ISSN |
0003-6935 |
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| Notes |
PMID:23262538 |
Approved |
no |
| Call Number |
LoNNe @ christopher.kyba @ |
Serial |
448 |
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| Author |
Kantermann, T. |
| Title |
Circadian biology: sleep-styles shaped by light-styles |
Type |
Journal Article |
| Year |
2013 |
Publication |
Current Biology : CB |
Abbreviated Journal |
Curr Biol |
| Volume |
23 |
Issue |
16 |
Pages |
R689-90 |
| Keywords |
Human Health; Circadian Clocks/*radiation effects; Female; Humans; *Lighting; Male; *Photoperiod; *Sunlight |
| Abstract |
Light and darkness are the main time cues synchronising all biological clocks to the external environment. This little understood evolutionary phenomenon is called circadian entrainment. A new study illuminates our understanding of how modern light- and lifestyles compromise circadian entrainment and impact our biological clocks. |
| Address |
Chronobiology – Centre for Behaviour and Neurosciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands. thomas@kantermann.de |
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English |
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Edition |
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| ISSN |
0960-9822 |
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| Notes |
PMID:23968925 |
Approved |
no |
| Call Number |
LoNNe @ christopher.kyba @ |
Serial |
501 |
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| Author |
Wright, K.P.J.; McHill, A.W.; Birks, B.R.; Griffin, B.R.; Rusterholz, T.; Chinoy, E.D. |
| Title |
Entrainment of the human circadian clock to the natural light-dark cycle |
Type |
Journal Article |
| Year |
2013 |
Publication |
Current Biology : CB |
Abbreviated Journal |
Curr Biol |
| Volume |
23 |
Issue |
16 |
Pages |
1554-1558 |
| Keywords |
Human Health; Adult; Circadian Clocks/*radiation effects; Female; Humans; *Lighting; Male; *Photoperiod; *Sunlight; Young Adult; Circadian Rhythm |
| Abstract |
The electric light is one of the most important human inventions. Sleep and other daily rhythms in physiology and behavior, however, evolved in the natural light-dark cycle [1], and electrical lighting is thought to have disrupted these rhythms. Yet how much the age of electrical lighting has altered the human circadian clock is unknown. Here we show that electrical lighting and the constructed environment is associated with reduced exposure to sunlight during the day, increased light exposure after sunset, and a delayed timing of the circadian clock as compared to a summer natural 14 hr 40 min:9 hr 20 min light-dark cycle camping. Furthermore, we find that after exposure to only natural light, the internal circadian clock synchronizes to solar time such that the beginning of the internal biological night occurs at sunset and the end of the internal biological night occurs before wake time just after sunrise. In addition, we find that later chronotypes show larger circadian advances when exposed to only natural light, making the timing of their internal clocks in relation to the light-dark cycle more similar to earlier chronotypes. These findings have important implications for understanding how modern light exposure patterns contribute to late sleep schedules and may disrupt sleep and circadian clocks. |
| Address |
Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309-0354, USA. kenneth.wright@colorado.edu |
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English |
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Edition |
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0960-9822 |
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| Notes |
PMID:23910656; PMCID:PMC4020279 |
Approved |
no |
| Call Number |
LoNNe @ christopher.kyba @ |
Serial |
505 |
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| Author |
Bullough, J.D.; Donnell, E.T.; Rea, M.S. |
| Title |
To illuminate or not to illuminate: roadway lighting as it affects traffic safety at intersections |
Type |
Journal Article |
| Year |
2013 |
Publication |
Accident; Analysis and Prevention |
Abbreviated Journal |
Accid Anal Prev |
| Volume |
53 |
Issue |
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Pages |
65-77 |
| Keywords |
Lighting; Accident Prevention/*methods; Accidents, Traffic/*prevention & control/psychology/statistics & numerical data; Cross-Sectional Studies; *Environment Design; Humans; *Lighting; Minnesota; Models, Statistical; Photoperiod; Psychomotor Performance; Regression Analysis; Safety/statistics & numerical data; Visual Perception |
| Abstract |
A two-pronged effort to quantify the impact of lighting on traffic safety is presented. In the statistical approach, the effects of lighting on crash frequency for different intersection types in Minnesota were assessed using count regression models. The models included many geometric and traffic control variables to estimate the association between lighting and nighttime and daytime crashes and the resulting night-to-day crash ratios. Overall, the presence of roadway intersection lighting was found to be associated with an approximately 12% lower night-to-day crash ratio than unlighted intersections. In the parallel analytical approach, visual performance analyses based on roadway intersection lighting practices in Minnesota were made for the same intersection types investigated in the statistical approach. The results of both approaches were convergent, suggesting that visual performance improvements from roadway lighting could serve as input for predicting improvements in crash frequency. A provisional transfer function allows transportation engineers to evaluate alternative lighting systems in the design phase so selections based on expected benefits and costs can be made. |
| Address |
Lighting Research Center, Rensselaer Polytechnic Institute, 21 Union Street, Troy, NY 12180, USA |
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English |
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0001-4575 |
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| Notes |
PMID:23377085 |
Approved |
no |
| Call Number |
LoNNe @ kagoburian @ |
Serial |
627 |
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