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Author Chellappa, S.L.; Steiner, R.; Blattner, P.; Oelhafen, P.; Gotz, T.; Cajochen, C. url  doi
openurl 
  Title Non-visual effects of light on melatonin, alertness and cognitive performance: can blue-enriched light keep us alert? Type (up) Journal Article
  Year 2011 Publication PloS one Abbreviated Journal PLoS One  
  Volume 6 Issue 1 Pages e16429  
  Keywords Circadian Rhythm/radiation effects; Cognition/*radiation effects; Color; Cross-Over Studies; Fluorescence; Humans; *Light; Male; Melatonin/*radiation effects; Reaction Time/*radiation effects; Young Adult; blue light  
  Abstract BACKGROUND: Light exposure can cascade numerous effects on the human circadian process via the non-imaging forming system, whose spectral relevance is highest in the short-wavelength range. Here we investigated if commercially available compact fluorescent lamps with different colour temperatures can impact on alertness and cognitive performance. METHODS: Sixteen healthy young men were studied in a balanced cross-over design with light exposure of 3 different light settings (compact fluorescent lamps with light of 40 lux at 6500K and at 2500K and incandescent lamps of 40 lux at 3000K) during 2 h in the evening. RESULTS: Exposure to light at 6500K induced greater melatonin suppression, together with enhanced subjective alertness, well-being and visual comfort. With respect to cognitive performance, light at 6500K led to significantly faster reaction times in tasks associated with sustained attention (Psychomotor Vigilance and GO/NOGO Task), but not in tasks associated with executive function (Paced Visual Serial Addition Task). This cognitive improvement was strongly related with attenuated salivary melatonin levels, particularly for the light condition at 6500K. CONCLUSIONS: Our findings suggest that the sensitivity of the human alerting and cognitive response to polychromatic light at levels as low as 40 lux, is blue-shifted relative to the three-cone visual photopic system. Thus, the selection of commercially available compact fluorescent lights with different colour temperatures significantly impacts on circadian physiology and cognitive performance at home and in the workplace.  
  Address Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland  
  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 1932-6203 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:21298068; PMCID:PMC3027693 Approved no  
  Call Number IDA @ john @ Serial 286  
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Author Cajochen, C.; Munch, M.; Kobialka, S.; Krauchi, K.; Steiner, R.; Oelhafen, P.; Orgul, S.; Wirz-Justice, A. url  doi
openurl 
  Title High sensitivity of human melatonin, alertness, thermoregulation, and heart rate to short wavelength light Type (up) Journal Article
  Year 2005 Publication The Journal of Clinical Endocrinology and Metabolism Abbreviated Journal J Clin Endocrinol Metab  
  Volume 90 Issue 3 Pages 1311-1316  
  Keywords Human Health; Adult; Body Temperature Regulation/physiology/*radiation effects; Circadian Rhythm/physiology/radiation effects; Color; Heart Rate/physiology/*radiation effects; Humans; *Light; Male; Melatonin/*metabolism; Retinal Cone Photoreceptor Cells/physiology; Sleep Stages/physiology/radiation effects; Wakefulness/physiology/*radiation effects  
  Abstract Light can elicit acute physiological and alerting responses in humans, the magnitude of which depends on the timing, intensity, and duration of light exposure. Here, we report that the alerting response of light as well as its effects on thermoregulation and heart rate are also wavelength dependent. Exposure to 2 h of monochromatic light at 460 nm in the late evening induced a significantly greater melatonin suppression than occurred with 550-nm monochromatic light, concomitant with a significantly greater alerting response and increased core body temperature and heart rate ( approximately 2.8 x 10(13) photons/cm(2)/sec for each light treatment). Light diminished the distal-proximal skin temperature gradient, a measure of the degree of vasoconstriction, independent of wavelength. Nonclassical ocular photoreceptors with peak sensitivity around 460 nm have been found to regulate circadian rhythm function as measured by melatonin suppression and phase shifting. Our findings-that the sensitivity of the human alerting response to light and its thermoregulatory sequelae are blue-shifted relative to the three-cone visual photopic system-indicate an additional role for these novel photoreceptors in modifying human alertness, thermophysiology, and heart rate.  
  Address Centre for Chronobiology, Psychiatric University Clinic, Wilhelm Kleinstr. 27, CH-4025 Basel, Switzerland. christian.cajochen@pukbasel.ch  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0021-972X ISBN Medium  
  Area Expedition Conference  
  Notes PMID:15585546 Approved no  
  Call Number LoNNe @ kagoburian @ Serial 728  
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Author Lely van der, S.; Frey, S.; Garbazza, C., Wirz-Justice, A.; Jenni, O.G.; Steiner, R.; Wolf, S.; Cajochen, C.; Bromundt, V.; Schmidt, C. url  doi
openurl 
  Title Blue Blocker Glasses as a Countermeasure for Alerting Effects of Evening Light-Emitting Diode Screen Exposure in Male Teenagers Type (up) Journal Article
  Year 2015 Publication Journal of Adolescent Health Abbreviated Journal J. Adolesc. Health  
  Volume 56 Issue Pages 113-119  
  Keywords LED screen use; Alerting effects of light; Sleepewake cycle; Melatonin; Sleepiness; Attention  
  Abstract Purpose: Adolescents prefer sleep and wake times that are considerably delayed compared with younger children or adults. Concomitantly, multimedia use in the evening is prevalent among teenagers and involves light exposure, particularly in the blue-wavelength range to which the biological clock and its associated arousal promotion system is the most sensitive. We investigated whether the use of blue lighteblocking glasses (BB) during the evening, while sitting in front of a light-emitting diode (LED) computer screen, favors sleep initiating mechanisms at the subjective, cognitive, and physiological level.

Methods: The ambulatory part of the study comprised 2 weeks during which the sleepewake cycle, evening light exposure, and multimedia screen use were monitored in thirteen 15- to 17-year-old healthy male volunteers. BB or clear lenses as control glasses were worn in a counterbalanced crossover design for 1 week each, during the evening hours while using LED screens. Afterward, participants entered the laboratory and underwent an evening blue lighteenriched LED screen exposure during which they wore the same glasses as during the preceding week. Salivary melatonin, subjective sleepiness, and vigilant attention were regularly assayed, and subsequent sleep was recorded by polysomnography.

Results: Compared with clear lenses, BB significantly attenuated LED-induced melatonin suppression in the evening and decreased vigilant attention and subjective alertness before bedtime. Visually scored sleep stages and behavioral measures collected the morning after were not modified.

Conclusions: BB glasses may be useful in adolescents as a countermeasure for alerting effects induced by light exposure through LED screens and therefore potentially impede the negative effects modern lighting imposes on circadian physiology in the evening.
 
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  Notes Approved no  
  Call Number LoNNe @ schroer @ Serial 1089  
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Author Chellappa, S.L.; Steiner, R.; Oelhafen, P.; Lang, D.; Gotz, T.; Krebs, J.; Cajochen, C. url  doi
openurl 
  Title Acute exposure to evening blue-enriched light impacts on human sleep Type (up) Journal Article
  Year 2013 Publication Journal of Sleep Research Abbreviated Journal J Sleep Res  
  Volume 22 Issue 5 Pages 573-580  
  Keywords Human Health  
  Abstract Light in the short wavelength range (blue light: 446-483 nm) elicits direct effects on human melatonin secretion, alertness and cognitive performance via non-image-forming photoreceptors. However, the impact of blue-enriched polychromatic light on human sleep architecture and sleep electroencephalographic activity remains fairly unknown. In this study we investigated sleep structure and sleep electroencephalographic characteristics of 30 healthy young participants (16 men, 14 women; age range 20-31 years) following 2 h of evening light exposure to polychromatic light at 6500 K, 2500 K and 3000 K. Sleep structure across the first three non-rapid eye movement non-rapid eye movement – rapid eye movement sleep cycles did not differ significantly with respect to the light conditions. All-night non-rapid eye movement sleep electroencephalographic power density indicated that exposure to light at 6500 K resulted in a tendency for less frontal non-rapid eye movement electroencephalographic power density, compared to light at 2500 K and 3000 K. The dynamics of non-rapid eye movement electroencephalographic slow wave activity (2.0-4.0 Hz), a functional index of homeostatic sleep pressure, were such that slow wave activity was reduced significantly during the first sleep cycle after light at 6500 K compared to light at 2500 K and 3000 K, particularly in the frontal derivation. Our data suggest that exposure to blue-enriched polychromatic light at relatively low room light levels impacts upon homeostatic sleep regulation, as indexed by reduction in frontal slow wave activity during the first non-rapid eye movement episode.  
  Address Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland; Cyclotron Research Center, University of Liege, Liege, Belgium  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0962-1105 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:23509952 Approved no  
  Call Number GFZ @ kyba @ Serial 2201  
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