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Author |
Wood, B.; Rea, M.S.; Plitnick, B.; Figueiro, M.G. |
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Title |
Light level and duration of exposure determine the impact of self-luminous tablets on melatonin suppression |
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Journal Article |
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Year |
2013 |
Publication |
Applied Ergonomics |
Abbreviated Journal |
Appl Ergon |
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Volume |
44 |
Issue |
2 |
Pages |
237-240 |
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Keywords |
Adolescent; *Computers, Handheld; Female; Humans; Light/*adverse effects; Male; Melatonin/*biosynthesis; Photoperiod; Saliva/*metabolism; Sleep/radiation effects; Time Factors; Young Adult; melatonin |
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Abstract |
Exposure to light from self-luminous displays may be linked to increased risk for sleep disorders because these devices emit optical radiation at short wavelengths, close to the peak sensitivity of melatonin suppression. Thirteen participants experienced three experimental conditions in a within-subjects design to investigate the impact of self-luminous tablet displays on nocturnal melatonin suppression: 1) tablets-only set to the highest brightness, 2) tablets viewed through clear-lens goggles equipped with blue light-emitting diodes that provided 40 lux of 470-nm light at the cornea, and 3) tablets viewed through orange-tinted glasses (dark control; optical radiation <525 nm approximately 0). Melatonin suppressions after 1-h and 2-h exposures to tablets viewed with the blue light were significantly greater than zero. Suppression levels after 1-h exposure to the tablets-only were not statistically different than zero; however, this difference reached significance after 2 h. Based on these results, display manufacturers can determine how their products will affect melatonin levels and use model predictions to tune the spectral power distribution of self-luminous devices to increase or to decrease stimulation to the circadian system. |
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Lighting Research Center, Rensselaer Polytechnic Institute, 21 Union Street, Troy, NY 12180, USA. woodb5@rpi.edu |
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0003-6870 |
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PMID:22850476 |
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IDA @ john @ |
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136 |
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Author |
Arendt, J. |
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Title |
Biological rhythms during residence in polar regions |
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Journal Article |
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Year |
2012 |
Publication |
Chronobiology International |
Abbreviated Journal |
Chronobiol Int |
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Volume |
29 |
Issue |
4 |
Pages |
379-394 |
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Keywords |
*Acclimatization; Activities of Daily Living; Affect; Antarctic Regions; Arctic Regions; *Biological Clocks; *Circadian Rhythm; *Cold Climate; *Cold Temperature; Energy Metabolism; Feeding Behavior; Humans; Melatonin/metabolism; Personnel Staffing and Scheduling; *Photoperiod; Seasonal Affective Disorder/physiopathology/prevention & control/psychology; *Seasons; Sleep; Sleep Disorders, Circadian Rhythm/etiology/physiopathology/*prevention & control/psychology; Time Factors; Workload; Workplace |
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At Arctic and Antarctic latitudes, personnel are deprived of natural sunlight in winter and have continuous daylight in summer: light of sufficient intensity and suitable spectral composition is the main factor that maintains the 24-h period of human circadian rhythms. Thus, the status of the circadian system is of interest. Moreover, the relatively controlled artificial light conditions in winter are conducive to experimentation with different types of light treatment. The hormone melatonin and/or its metabolite 6-sulfatoxymelatonin (aMT6s) provide probably the best index of circadian (and seasonal) timing. A frequent observation has been a delay of the circadian system in winter. A skeleton photoperiod (2 x 1-h, bright white light, morning and evening) can restore summer timing. A single 1-h pulse of light in the morning may be sufficient. A few people desynchronize from the 24-h day (free-run) and show their intrinsic circadian period, usually >24 h. With regard to general health in polar regions, intermittent reports describe abnormalities in various physiological processes from the point of view of daily and seasonal rhythms, but positive health outcomes are also published. True winter depression (SAD) appears to be rare, although subsyndromal SAD is reported. Probably of most concern are the numerous reports of sleep problems. These have prompted investigations of the underlying mechanisms and treatment interventions. A delay of the circadian system with “normal” working hours implies sleep is attempted at a suboptimal phase. Decrements in sleep efficiency, latency, duration, and quality are also seen in winter. Increasing the intensity of ambient light exposure throughout the day advanced circadian phase and was associated with benefits for sleep: blue-enriched light was slightly more effective than standard white light. Effects on performance remain to be fully investigated. At 75 degrees S, base personnel adapt the circadian system to night work within a week, in contrast to temperate zones where complete adaptation rarely occurs. A similar situation occurs on high-latitude North Sea oil installations, especially when working 18:00-06:00 h. Lack of conflicting light exposure (and “social obligations”) is the probable explanation. Many have problems returning to day work, showing circadian desynchrony. Timed light treatment again has helped to restore normal phase/sleep in a small number of people. Postprandial response to meals is compromised during periods of desynchrony with evidence of insulin resistance and elevated triglycerides, risk factors for heart disease. Only small numbers of subjects have been studied intensively in polar regions; however, these observations suggest that suboptimal light conditions are deleterious to health. They apply equally to people living in temperate zones with insufficient light exposure. |
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Centre for Chronobiology, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK. arendtjo@gmail.com |
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0742-0528 |
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PMID:22497433; PMCID:PMC3793275 |
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IDA @ john @ |
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143 |
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Author |
Vollmer, C.; Michel, U.; Randler, C. |
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Title |
Outdoor light at night (LAN) is correlated with eveningness in adolescents |
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Journal Article |
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Year |
2012 |
Publication |
Chronobiology International |
Abbreviated Journal |
Chronobiol Int |
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Volume |
29 |
Issue |
4 |
Pages |
502-508 |
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Keywords |
Adolescent; *Adolescent Behavior/drug effects; Biological Clocks; Central Nervous System Stimulants/administration & dosage; *Circadian Rhythm/drug effects; Computers; Cross-Sectional Studies; Female; Germany; Humans; *Light; Lighting; Male; *Photic Stimulation; *Photoperiod; Questionnaires; *Sleep/drug effects; Television; Time Factors; Video Games; *Wakefulness/drug effects |
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External zeitgebers synchronize the human circadian rhythm of sleep and wakefulness. Humans adapt their chronotype to the day-night cycle, the strongest external zeitgeber. The human circadian rhythm shifts to evening-type orientation when daylight is prolonged into the evening and night hours by artificial light sources. Data from a survey of 1507 German adolescents covering questions about chronotype and electronic screen media use combined with nocturnal satellite image data suggest a relationship between chronotype and artificial nocturnal light. Adolescents living in brightly illuminated urban districts had a stronger evening-type orientation than adolescents living in darker and more rural municipalities. This result persisted when controlling for time use of electronic screen media, intake of stimulants, type of school, age, puberty status, time of sunrise, sex, and population density. Time spent on electronic screen media use-a source of indoor light at night-is also correlated with eveningness, as well as intake of stimulants, age, and puberty status, and, to a lesser degree, type of school and time of sunrise. Adequate urban development design and parents limiting adolescents' electronic screen media use in the evening could help to adjust adolescents' zeitgeber to early school schedules when they provide appropriate lighting conditions for daytime and for nighttime. |
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Department of Biology, University of Education Heidelberg, Germany. vollmer@ph-heidelberg.de |
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0742-0528 |
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PMID:22214237 |
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IDA @ john @ |
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150 |
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Santhi, N.; Thorne, H.C.; van der Veen, D.R.; Johnsen, S.; Mills, S.L.; Hommes, V.; Schlangen, L.J.M.; Archer, S.N.; Dijk, D.-J. |
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Title |
The spectral composition of evening light and individual differences in the suppression of melatonin and delay of sleep in humans |
Type |
Journal Article |
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Year |
2012 |
Publication |
Journal of Pineal Research |
Abbreviated Journal |
J Pineal Res |
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Volume |
53 |
Issue |
1 |
Pages |
47-59 |
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Keywords |
Human Health; Adult; *Circadian Clocks; Cross-Sectional Studies; Electroencephalography; Female; Humans; Male; Melatonin/*metabolism; Photic Stimulation; *Photoperiod; Rod Opsins/*metabolism; *Sleep; *Sleep Disorders, Circadian Rhythm/etiology/metabolism/physiopathology; Time Factors |
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The effect of light on circadian rhythms and sleep is mediated by a multi-component photoreceptive system of rods, cones and melanopsin-expressing intrinsically photosensitive retinal ganglion cells. The intensity and spectral sensitivity characteristics of this system are to be fully determined. Whether the intensity and spectral composition of light exposure at home in the evening is such that it delays circadian rhythms and sleep also remains to be established. We monitored light exposure at home during 6-8wk and assessed light effects on sleep and circadian rhythms in the laboratory. Twenty-two women and men (23.1+/-4.7yr) participated in a six-way, cross-over design using polychromatic light conditions relevant to the light exposure at home, but with reduced, intermediate or enhanced efficacy with respect to the photopic and melanopsin systems. The evening rise of melatonin, sleepiness and EEG-assessed sleep onset varied significantly (P<0.01) across the light conditions, and these effects appeared to be largely mediated by the melanopsin, rather than the photopic system. Moreover, there were individual differences in the sensitivity to the disruptive effect of light on melatonin, which were robust against experimental manipulations (intra-class correlation=0.44). The data show that light at home in the evening affects circadian physiology and imply that the spectral composition of artificial light can be modified to minimize this disruptive effect on sleep and circadian rhythms. These findings have implications for our understanding of the contribution of artificial light exposure to sleep and circadian rhythm disorders such as delayed sleep phase disorder. |
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Surrey Sleep Research Centre, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK. n.santhi@surrey.ac.uk |
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0742-3098 |
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PMID:22017511 |
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LoNNe @ kagoburian @ |
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802 |
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Behar-Cohen, F.; Martinsons, C.; Vienot, F.; Zissis, G.; Barlier-Salsi, A.; Cesarini, J.P.; Enouf, O.; Garcia, M.; Picaud, S.; Attia, D. |
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Title |
Light-emitting diodes (LED) for domestic lighting: any risks for the eye? |
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Journal Article |
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Year |
2011 |
Publication |
Progress in Retinal and eye Research |
Abbreviated Journal |
Prog Retin Eye Res |
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Volume |
30 |
Issue |
4 |
Pages |
239-257 |
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Keywords |
Animals; Biomass; Circadian Rhythm/physiology; Environmental Exposure; Eye Diseases/*etiology/pathology/physiopathology; Humans; *Light/adverse effects; Lighting/*methods; Reflex, Pupillary/physiology; Retina/pathology; Risk Assessment; *Semiconductors; Time Factors |
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Light-emitting diodes (LEDs) are taking an increasing place in the market of domestic lighting because they produce light with low energy consumption. In the EU, by 2016, no traditional incandescent light sources will be available and LEDs may become the major domestic light sources. Due to specific spectral and energetic characteristics of white LEDs as compared to other domestic light sources, some concerns have been raised regarding their safety for human health and particularly potential harmful risks for the eye. To conduct a health risk assessment on systems using LEDs, the French Agency for Food, Environmental and Occupational Health & Safety (ANSES), a public body reporting to the French Ministers for ecology, for health and for employment, has organized a task group. This group consisted physicists, lighting and metrology specialists, retinal biologist and ophthalmologist who have worked together for a year. Part of this work has comprised the evaluation of group risks of different white LEDs commercialized on the French market, according to the standards and found that some of these lights belonged to the group risk 1 or 2. This paper gives a comprehensive analysis of the potential risks of white LEDs, taking into account pre-clinical knowledge as well as epidemiologic studies and reports the French Agency's recommendations to avoid potential retinal hazards. |
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Inserm UMRS 872, Physiopathology of Ocular Diseases: Therapeutic Innovations, Centre de Recherche des Cordeliers, Paris, France. Francine.behar-cohen@crc.jussieur.fr |
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1350-9462 |
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PMID:21600300 |
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IDA @ john @ |
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240 |
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