scholarly journals Predicting melatonin suppression by light in humans: unifying photoreceptor‐based equivalent daylight illuminances, spectral composition, timing and duration of light exposure

2022 ◽  
Author(s):  
M. Giménez ◽  
O. Stefani ◽  
C. Cajochen ◽  
D. Lang ◽  
G. Deuring ◽  
...  
Keyword(s):  
Light Exposure ◽  
Spectral Composition ◽  
Melatonin Suppression

scholarly journals Light Exposure during Days with Night, Outdoor, and Indoor Work

2019 ◽  
Vol 63 (6) ◽  
pp. 651-665 ◽  
Author(s):  
Stine Daugaard ◽  
Jakob Markvart ◽  
Jens Peter Bonde ◽  
Jens Christoffersen ◽  
Anne Helene Garde ◽  
...  
Keyword(s):  
Light Intensity ◽  
Light Exposure ◽  
Spectral Composition ◽  
Working Hours ◽  
Well Being ◽  
Outdoor Workers ◽  
Light Levels ◽  
Light Intensities ◽  
Treatment Of Depression ◽  
Night Shifts

Abstract Objective To assess light exposure during days with indoor, outdoor, and night work and days off work. Methods Light intensity was continuously recorded for 7 days across the year among indoor (n = 170), outdoor (n = 151), and night workers (n = 188) in Denmark (55–56°N) equipped with a personal light recorder. White light intensity, duration above 80, 1000, and 2500 lux, and proportion of red, green, and blue light was depicted by time of the day and season for work days and days off work. Results Indoor workers’ average light exposure only intermittently exceeded 1000 lux during daytime working hours in summer and never in winter. During daytime working hours, most outdoor workers exceeded 2500 lux in summer and 1000 lux in winter. Night workers spent on average 10–50 min >80 lux when working night shifts. During days off work, indoor and night workers were exposed to higher light intensities than during work days and few differences were seen between indoor, outdoor, and night workers. The spectral composition of light was similar for indoor, outdoor, and night workers during days at and off work. Conclusion The night workers of this study were during night hours on average exposed for a limited time to light intensities expected to suppress melatonin. The indoor workers were exposed to light levels during daylight hours that may reduce general well-being and mood, especially in winter. Outdoor workers were during summer daylight hours exposed to light levels comparable to those used for the treatment of depression.

scholarly journals Dark regeneration of rhodopsin in crayfish photoreceptors.

1984 ◽  
Vol 84 (1) ◽  
pp. 63-81 ◽  
Author(s):  
T W Cronin ◽  
T H Goldsmith
Keyword(s):  
Blue Light ◽  
Light Adaptation ◽  
Light Exposure ◽  
Spectral Composition ◽  
Complete Recovery ◽  
Regeneration System ◽  
Total Pigment ◽  
Accessory Pigment ◽  
Rate Of Recovery ◽  
Turn Over

The eyes of crayfish were exposed to lights of known spectral composition, and the course of regeneration was followed in the dark by measuring the content of rhodopsin and metarhodopsin in single rhabdoms isolated at various times after the adaptation, using an assay that is based on the fluorescence of metarhodopsin. Complete recovery requires several days in the dark after intense adaptation to orange light, but requires less than 2 d after blue light exposure. Following an orange light exposure with blue produces recovery kinetics characteristic of the blue light exposure alone. This quickening of recovery occurs whether the receptors are exposed to blue light either immediately or many hours after the original exposure to orange. Conversely, following blue light adaptation with orange leads to slow recovery, which is characteristic of orange alone. Recovery from long-wavelength adaptation is slower principally because many rhabdoms seem to delay the onset of regeneration. We suggest that the regeneration system is itself photosensitive, and after orange light adaptation the supply of active chromophore (presumably 11-cis retinal) limits the rate of recovery. Once started, recovery proceeds slowly and continuously, and the total pigment concentration (rhodopsin plus metarhodopsin) in the rhabdomeric membrane remains approximately constant. Within hours after intense adapting exposures, the rhabdoms become altered in appearance, the surfaces become coated with accessory pigment, and the bands of microvilli are less distinct. These changes persist until recovery of rhodopsin proceeds, which suggests that visual pigment regeneration results from addition of newly synthesized rhodopsin associated with membrane turn-over.

scholarly journals What is the "spectral diet" of humans?

2019 ◽  
Author(s):  
Forrest Webler ◽  
Manuel Spitschan ◽  
Russell Foster ◽  
Marilyne Andersen ◽  
Stuart Peirson
Keyword(s):  
Spatial Distribution ◽  
Visual Perception ◽  
Light Exposure ◽  
Spectral Composition ◽  
Spatial Vision ◽  
Natural Image ◽  
Natural Light ◽  
Natural Image Statistics ◽  
The World ◽  
Long Time

Our visual perception of the world – seeing form and colour or navigating the environment – depends on the interaction of light and matter in the environment. Light also has a more fundamental role in regulating rhythms in physiology and behaviour, as well as in the acute secretion of hormones like melatonin and changes in alertness, where light exposure at short, medium and long-time scales has different effects on these visual and non-visual functions. Yet patterns of light exposure in the real world are inherently messy: we move in and out of buildings and are therefore exposed to mixtures of artificial and natural light, and the physical makeup of our environment can also drastically alter the spectral composition and spatial distribution of the illuminant light. In spatial vision, the examination of natural image statistics has proven to be an important driver in research. Here, we expand this concept to the spectral domain and develop the concept of the “spectral diet” of humans.

scholarly journals 0240 Nocturnal Melatonin Suppression In Adolescents And Adults For Different Levels, Spectra And Durations Of Light Exposure

SLEEP ◽  
2019 ◽  
Vol 42 (Supplement_1) ◽  
pp. A99-A99
Author(s):  
Rohan M Nagare ◽  
Mark S Rea ◽  
Barbara A Plitnick ◽  
Mariana G Figueiro
Keyword(s):  
Light Exposure ◽  
Melatonin Suppression ◽  
Adolescents And Adults ◽  
Different Levels

scholarly journals Differential response of planktonic primary, bacterial, and dimethylsulfide production rates to static vs. dynamic light exposure in upper mixed-layer summer sea waters

2013 ◽  
Vol 10 (12) ◽  
pp. 7983-7998 ◽  
Author(s):  
M. Galí ◽  
R. Simó ◽  
G. L. Pérez ◽  
C. Ruiz-González ◽  
H. Sarmento ◽  
...  
Keyword(s):  
Primary Production ◽  
Mixed Layer ◽  
Light Exposure ◽  
Spectral Composition ◽  
Total Solar Irradiance ◽  
Depth Range ◽  
Biogeochemical Processes ◽  
Physiological Indicators ◽  
Upper Mixed Layer

Abstract. Microbial plankton experience short-term fluctuations in total solar irradiance and in its spectral composition as they are vertically moved by turbulence in the oceanic upper mixed layer (UML). The fact that the light exposure is not static but dynamic may have important consequences for biogeochemical processes and ocean–atmosphere fluxes. However, most biogeochemical processes other than primary production, like bacterial production or dimethylsulfide (DMS) production, are seldom measured in sunlight and even less often in dynamic light fields. We conducted four experiments in oligotrophic summer stratified Mediterranean waters, where a sample from the UML was incubated in ultraviolet (UV)-transparent bottles at three fixed depths within the UML and on a vertically moving basket across the same depth range. We assessed the response of the phyto- and bacterioplankton community with physiological indicators based on flow cytometry singe-cell measurements, fast repetition rate fluorometry (FRRf), phytoplankton pigment concentrations and particulate light absorption. Dynamic light exposure caused a subtle disruption of the photoinhibition and photoacclimation processes associated with ultraviolet radiation (UVR), which slightly alleviated bacterial photoinhibition but did not favor primary production. Gross DMS production (GPDMS) decreased sharply with depth in parallel to shortwave UVR, and displayed a dose-dependent response that mixing did not significantly disrupt. To our knowledge, we provide the first measurements of GPDMS under in situ UV-inclusive optical conditions.

Seasonal Affective Disorder: Response to Light as Measured by Electroencephalogram, Melatonin Suppression, and Cerebral Blood Flow

1993 ◽  
Vol 163 (3) ◽  
pp. 327-331 ◽  
Author(s):  
D. G. M. Murphy ◽  
D. M. Murphy ◽  
M. Abbas ◽  
E. Palazidou ◽  
C. Binnie ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Contrast Sensitivity ◽  
Seasonal Affective Disorder ◽  
Light Exposure ◽  
Physiological Responses ◽  
Response To Treatment ◽  
Small Pilot Study ◽  
Melatonin Suppression ◽  
Significant Difference

This study was designed to test the hypothesis that patients with SAD have significantly different physiological responses to light than healthy age- and sex-matched controls. We studied retinal contrast sensitivity, visual evoked EEG responses, and melatonin suppression by, and cerebral blood flow response to, full-spectrum artificial daylight. There was no significant difference between 10 patients and 11 controls in retinal contrast sensitivity, or amplitude or latency of N2, P2, P100 or P300 on EEG. We compared melatonin suppression in 12 SAD patients and 12 controls. During exposure to 500 lux and 1500 lux artificial daylight both the SAD patients and controls had a significant melatonin percentage suppression; however, the percentage suppression did not differ significantly between the SAD patients and the controls. In addition, we carried out a small pilot study into the effect of light on cerebral blood flow in four SAD patients and four controls. Before exposure to 1500 lux artificial daylight there was no significant difference between patients and controls in global, regional or cerebral hemispheric blood flow. After light exposure the SAD patients and controls had a significantly different percentage change in cerebral blood flow. We suggest that patients with SAD do not have significantly physiological responses to light than controls, except perhaps in cerebral blood flow. Furthermore, mechanisms other than supersensitivity of melatonin suppression must explain both the pathophysiology of the disorder and its response to treatment with light.

scholarly journals Light and chronobiology: implications for health and disease

2012 ◽  
Vol 14 (4) ◽  
pp. 448-453 ◽  
Keyword(s):  
Cognitive Performance ◽  
Light Exposure ◽  
Biological Clock ◽  
Spectral Composition ◽  
Light Therapy ◽  
Lighting Conditions ◽  
Environmental Light ◽  
Health And Disease ◽  
Peripheral Clocks ◽  
Indoor Lighting

Environmental light synchronizes the primary mammalian biological clock in the suprachiasmatic nuclei, as well as many peripheral clocks in tissues and cells, to the solar 24-hour day. Light is the strongest synchronizing agent (zeitgeber) for the circadian system, and therefore keeps most biological and psychological rhythms internally synchronized, which is important for optimum function. Circadian sleep-wake disruptions and chronic circadian misalignment, as often observed in psychiatric and neurodegenerative illness, can be treated with light therapy. The beneficial effect on circadian synchronization, sleep quality, mood, and cognitive performance depends on timing, intensity, and spectral composition of light exposure. Tailoring and optimizing indoor lighting conditions may be an approach to improve wellbeing, alertness, and cognitive performance and, in the long term, producing health benefits.

Brain, Eyes, Light: Biological Electrical Magnetism of Light and Neurorehabilitation of Cognitive Impairment

2019 ◽  
Vol 5 (12) ◽  
pp. 129-155 ◽  
Author(s):  
V. Pyatin ◽  
N. Romanchuk ◽  
P. Romanchuk ◽  
A. Volobuev
Keyword(s):  
Cognitive Impairment ◽  
Hybrid Methods ◽  
Homo Sapiens ◽  
Light Exposure ◽  
Multimodal Interaction ◽  
Spectral Composition ◽  
Cognitive Disorders ◽  
Endocrine Disorders ◽  
Sleep Wake Disorders ◽  
The Brain

Biological electrical magnetism of light and neural networks of the brain is the adaptation and optimization of external and internal lighting conditions (type, nature, duration) to improve the cognitive brain. Homo sapiens brain operates in a 24-hour biological electrical magnetic environment. Light is the strongest synchronizing signal for the circadian system, and therefore keeps most biological and psychological rhythms internally synchronized, which is important for the optimal functioning of H. sapiens brain. Circadian Sleep–Wake disorders and chronic circadian misalignment, often seen in psychiatric and neurodegenerative diseases, may be effective in neurorehabilitation of cognitive impairment. Beneficial effects on circadian synchronization, sleep quality, mood and cognitive performance-depend on the time, intensity and spectral composition of light exposure. Multidisciplinary and multimodal interaction in the triad “brain–eyes–vessels” allows to identify early biomarkers of both General accelerated and pathological aging, and timely diagnose neurodegeneration, and conduct effective neurorehabilitation of cognitive disorders. Control and treatment of vascular risk factors and endocrine disorders can reduce the prevalence of long-term disability among the elderly population. Combined and hybrid methods of neuroimaging in conjunction with artificial intelligence technologies, allow to understand and diagnose neurological disorders and find new methods of neurorehabilitation and medical and social support that will lead to improved mental health. To restore circadian neuroplasticity of the brain, a multimodal scheme is proposed: circadian glasses, functional nutrition and physical activity. A combined and hybrid cluster in the diagnosis, treatment, prevention and rehabilitation of cognitive disorders and cognitive disorders has been developed and implemented.

Effect of photoselective filters on the physical and chemical traits of vine-ripened tomato fruits

2005 ◽  
Vol 85 (2) ◽  
pp. 439-446 ◽  
Author(s):  
Hélène Gautier ◽  
Aline Rocci ◽  
Michel Buret ◽  
Dominique Grasselly ◽  
Yvon Dumas ◽  
...  
Keyword(s):  
Vitamin C ◽  
Fruit Ripening ◽  
Light Exposure ◽  
Soluble Sugars ◽  
Red Light ◽  
Spectral Composition ◽  
Titratable Acidity ◽  
Infrared Light ◽  
Tomato Fruits ◽  
Β Carotene

The effects of several wavelength selective light filters placed on developing mature green tomato fruits were studied to determine whether light environment during fruit ripening has an impact on fruit composition. Juice titratable acidity and fruit fresh and dry weight varied little with the different filters. Reducing the red/far-red light ratio with a green filter to simulate vegetation shade slightly delayed ripening. Reducing infrared light (700-1100 nm) reduced vitamin C and soluble sugars content. A drastic reduction in photosynthetic light (97%) reduced both β-carotene (-23%) and lycopene (-29%) contents and red coloration (-21%). Significant correlations were found among the content of soluble sugars, vitamin C and lycopene, but these components increased differently according to the spectral composition of the light transmitted to the fruit. The content of lycopene and β-carotene increased with exposure to photosynthetic radiation and more precisely with exposure to blue light. In contrast, the content of vitamin C and sugar increased with infrared light exposure. Key words: β-carotene, photoselective filters or shading, fruit ripening, fruit environment, lycopene, Lycopersicon esculentum, tomato, vitamin C

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