1
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Spitschan M. Selecting, implementing and evaluating control and placebo conditions in light therapy and light-based interventions. Ann Med 2024; 56:2298875. [PMID: 38329797 PMCID: PMC10854444 DOI: 10.1080/07853890.2023.2298875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 12/20/2023] [Indexed: 02/09/2024] Open
Abstract
Introduction: Light profoundly influences human physiology, behaviour and cognition by affecting various functions through light-sensitive cells in the retina. Light therapy has proven effective in treating seasonal depression and other disorders. However, designing appropriate control conditions for light-based interventions remains a challenge.Materials and methods: This article presents a novel framework for selecting, implementing and evaluating control conditions in light studies, offering theoretical foundations and practical guidance. It reviews the fundamentals of photoreception and discusses control strategies such as dim light, darkness, different wavelengths, spectral composition and metameric conditions. Special cases like dynamic lighting, simulated dawn and dusk, complex interventions and studies involving blind or visually impaired patients are also considered.Results: The practical guide outlines steps for selection, implementation, evaluation and reporting, emphasizing the importance of α-opic calculations and physiological validation.Conclusion: In conclusion, constructing effective control conditions is crucial for demonstrating the efficacy of light interventions in various research scenarios.
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Affiliation(s)
- Manuel Spitschan
- Max Planck Institute for Biological Cybernetics, Translational Sensory & Circadian Neuroscience, Tübingen, Germany
- Technical University of Munich, TUM School of Medicine and Health, Chronobiology & Health, Munich, Germany
- Technical University of Munich, TUM Institute for Advanced Study (TUM-IAS), Garching, Germany
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2
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Longcore T, Villanueva SAMB, Nguyen-Ngo K, Ghiani CA, Harrison B, Colwell CS. Relative importance of intensity and spectrum of artificial light at night in disrupting behavior of a nocturnal rodent. J Exp Biol 2024; 227:jeb247235. [PMID: 38873751 DOI: 10.1242/jeb.247235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2023] [Accepted: 06/01/2024] [Indexed: 06/15/2024]
Abstract
The influence of light spectral properties on circadian rhythms is of substantial interest to laboratory-based investigation of the circadian system and to field-based understanding of the effects of artificial light at night. The trade-offs between intensity and spectrum regarding masking behaviors are largely unknown, even for well-studied organisms. We used a custom LED illumination system to document the response of wild-type house mice (Mus musculus) to 1-h nocturnal exposure of all combinations of four intensity levels (0.01, 0.5, 5 and 50 lx) and three correlated color temperatures (CCT; 1750, 1950 and 3000 K). Higher intensities of light (50 lx) suppressed cage activity substantially, and consistently more for the higher CCT light (91% for 3000 K, 53% for 1750 K). At the lowest intensity (0.01 lx), mean activity was increased, with the greatest increases for the lowest CCT (12.3% increase at 1750 K, 3% increase at 3000 K). Multiple linear regression confirmed the influence of both CCT and intensity on changes in activity, with the scaled effect size of intensity 3.6 times greater than that of CCT. Activity suppression was significantly lower for male than for female mice. Assessment of light-evoked cFos expression in the suprachiasmatic nucleus at 50 lx showed no significant difference between high and low CCT exposure. The significant differences by spectral composition illustrate a need to account for light spectrum in circadian studies of behavior, and confirm that spectral controls can mitigate some, but certainly not all, of the effects of light pollution on species in the wild.
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Affiliation(s)
- Travis Longcore
- UCLA Institute of the Environment and Sustainability, 619 Charles E. Young Drive East, La Kretz Hall, Suite 300, Box 951496, Los Angeles, CA 90095-1496, USA
| | - Sophia Anne Marie B Villanueva
- UCLA Department of Integrative Biology and Physiology, 612 Charles E. Young Drive East, Box 957246, Los Angeles, CA 90095-7246, USA
- UCLA Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry and Biobehavioral Sciences, 760 Westwood Plaza, Los Angeles, CA 90095, USA
| | - Kyle Nguyen-Ngo
- UCLA Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry and Biobehavioral Sciences, 760 Westwood Plaza, Los Angeles, CA 90095, USA
| | - Cristina A Ghiani
- UCLA Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry and Biobehavioral Sciences, 760 Westwood Plaza, Los Angeles, CA 90095, USA
- UCLA Department of Pathology and Laboratory Medicine, 10833 Le Conte Avenue, Los Angeles, CA 90095-1732, USA
| | - Benjamin Harrison
- Korrus, Inc., 837 North Spring Street, Suite 103, Los Angeles, CA 90012, USA
| | - Christopher S Colwell
- UCLA Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry and Biobehavioral Sciences, 760 Westwood Plaza, Los Angeles, CA 90095, USA
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3
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Farag HI, Murphy BA, Templeman JR, Hanlon C, Joshua J, Koch TG, Niel L, Shoveller AK, Bedecarrats GY, Ellison A, Wilcockson D, Martino TA. One Health: Circadian Medicine Benefits Both Non-human Animals and Humans Alike. J Biol Rhythms 2024; 39:237-269. [PMID: 38379166 PMCID: PMC11141112 DOI: 10.1177/07487304241228021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Circadian biology's impact on human physical health and its role in disease development and progression is widely recognized. The forefront of circadian rhythm research now focuses on translational applications to clinical medicine, aiming to enhance disease diagnosis, prognosis, and treatment responses. However, the field of circadian medicine has predominantly concentrated on human healthcare, neglecting its potential for transformative applications in veterinary medicine, thereby overlooking opportunities to improve non-human animal health and welfare. This review consists of three main sections. The first section focuses on the translational potential of circadian medicine into current industry practices of agricultural animals, with a particular emphasis on horses, broiler chickens, and laying hens. The second section delves into the potential applications of circadian medicine in small animal veterinary care, primarily focusing on our companion animals, namely dogs and cats. The final section explores emerging frontiers in circadian medicine, encompassing aquaculture, veterinary hospital care, and non-human animal welfare and concludes with the integration of One Health principles. In summary, circadian medicine represents a highly promising field of medicine that holds the potential to significantly enhance the clinical care and overall health of all animals, extending its impact beyond human healthcare.
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Affiliation(s)
- Hesham I. Farag
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
- Centre for Cardiovascular Investigations, University of Guelph, Guelph, ON, Canada
| | - Barbara A. Murphy
- School of Agriculture and Food Science, University College, Dublin, Ireland
| | - James R. Templeman
- Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
| | - Charlene Hanlon
- Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
- Department of Poultry Science, Auburn University, Auburn, Alabama, USA
| | - Jessica Joshua
- Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - Thomas G. Koch
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - Lee Niel
- Department of Pathobiology, University of Guelph, Guelph, ON, Canada
| | - Anna K. Shoveller
- Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
| | | | - Amy Ellison
- School of Natural Sciences, Bangor University, Bangor, UK
| | - David Wilcockson
- Department of Life Sciences, Aberystwyth University, Aberystwyth, UK
| | - Tami A. Martino
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
- Centre for Cardiovascular Investigations, University of Guelph, Guelph, ON, Canada
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4
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Schöllhorn I, Stefani O, Lucas RJ, Spitschan M, Epple C, Cajochen C. The Impact of Pupil Constriction on the Relationship Between Melanopic EDI and Melatonin Suppression in Young Adult Males. J Biol Rhythms 2024; 39:282-294. [PMID: 38348477 PMCID: PMC11141089 DOI: 10.1177/07487304241226466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
Abstract
The pupil modulates the amount of light that reaches the retina. Not only luminance but also the spectral distribution defines the pupil size. Previous research has identified steady-state pupil size and melatonin attenuation to be predominantly driven by melanopsin, which is expressed by a unique subgroup of intrinsically photosensitive retinal ganglion cells (ipRGCs) that are sensitive to short-wavelength light (~480 nm). Here, we aimed to selectively target the melanopsin system during the evening, while measuring steady-state pupil size and melatonin concentrations under commonly experienced evening light levels (<90 lx). Therefore, we used a five-primary display prototype to generate light conditions that were matched in terms of L-, M-, and S-cone-opic irradiances, but with high and low melanopic irradiances (~3-fold difference). Seventy-two healthy, male participants completed a 2-week study protocol. The volunteers were assigned to one of the four groups that differed in luminance levels (27-285 cd/m2). Within the four groups, each volunteer was exposed to a low melanopic (LM) and a high melanopic (HM) condition. The two 17-h study protocols comprised 3.5 h of light exposure starting 4 h before habitual bedtime. Median pupil size was significantly smaller during HM than LM in all four light intensity groups. In addition, we observed a significant correlation between melanopic weighted corneal illuminance (melanopic equivalent daylight illuminance [mEDI]) and pupil size, such that higher mEDI values were associated with smaller pupil size. Using pupil size to estimate retinal irradiance showed a qualitatively similar goodness of fit as mEDI for predicting melatonin suppression. Based on our results here, it remains appropriate to use melanopic irradiance measured at eye level when comparing light-dependent effects on evening melatonin concentrations in healthy young people at rather low light levels.
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Affiliation(s)
- Isabel Schöllhorn
- Centre for Chronobiology, Psychiatric Hospital, University of Basel, Basel, Switzerland
- Research Platform Molecular and Cognitive Neurosciences (MCN), University of Basel, Basel, Switzerland
| | - Oliver Stefani
- Centre for Chronobiology, Psychiatric Hospital, University of Basel, Basel, Switzerland
- Lucerne University of Applied Sciences and Arts, Lucerne, Switzerland
| | - Robert J Lucas
- Centre for Biological Timing, School of Biology, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Manuel Spitschan
- Translational Sensory & Circadian Neuroscience, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
- Chronobiology & Health, Technical University of Munich, Munich, Germany
- TUM Institute for Advanced Study (TUM-IAS), Technical University of Munich, Munich, Germany
| | - Christian Epple
- Centre for Chronobiology, Psychiatric Hospital, University of Basel, Basel, Switzerland
| | - Christian Cajochen
- Centre for Chronobiology, Psychiatric Hospital, University of Basel, Basel, Switzerland
- Research Platform Molecular and Cognitive Neurosciences (MCN), University of Basel, Basel, Switzerland
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5
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Odebrecht Vergne de Abreu AC, Alves Braga de Oliveira M, Alquati T, Tonon AC, de Novaes Reis M, Camargo Rossi A, Sbaraini Bonatto F, Paz Hidalgo M. Use of Light Protection Equipment at Night Reduces Time Until Discharge From the Neonatal Intensive Care Unit: A Randomized Interventional Study. J Biol Rhythms 2024; 39:68-78. [PMID: 37846856 DOI: 10.1177/07487304231201752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
Newborn infants' circadian systems are not completely developed and rely on external temporal cues for synchronizing their biological rhythms to the environment. In neonatal intensive care units (NICUs), lighting is usually continuous or irregular and infants are exposed to artificial light at night, which can have negative health consequences. Therefore, the aim of this study was to evaluate the impact of the use of individual light protection equipment at night on the development and growth of preterm neonates. Infants born at less than 37 gestational weeks who no longer needed constant intensive care were admitted into a newborn nursery and randomized to either use eye masks at night (intervention, n = 21) or not (control, n = 20). Infants who used eye protection at night were discharged earlier than those in the control group (8 [5] vs 12 [3.75] days; p < 0.05). A greater variation within the day in heart rate was observed in the intervention group, with lower values of beats per minute at 1400 and 2000 h. There was no significant difference in weight gain between groups. In view of our results and of previous findings present in the literature, we suggest that combining a darkened environment at night with individual light protection devices creates better conditions for the development of preterm infants in the NICU. In addition, eye masks are an affordable and simple-to-use tool that can reduce hospitalization costs by decreasing the number of days spent in the NICU.
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Affiliation(s)
- Ana Carolina Odebrecht Vergne de Abreu
- Laboratório de Cronobiologia e Sono, Hospital de Clínicas de Porto Alegre (HCPA), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Melissa Alves Braga de Oliveira
- Laboratório de Cronobiologia e Sono, Hospital de Clínicas de Porto Alegre (HCPA), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
- Graduate Program in Psychiatry and Behavioral Sciences, School of Medicine, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Tamila Alquati
- Neonatology Department, Hospital Nossa Senhora de Pompéia, Caxias do Sul, RS, Brazil
| | - André Comiran Tonon
- Laboratório de Cronobiologia e Sono, Hospital de Clínicas de Porto Alegre (HCPA), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Mariana de Novaes Reis
- Laboratório de Cronobiologia e Sono, Hospital de Clínicas de Porto Alegre (HCPA), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Augusto Camargo Rossi
- Laboratório de Cronobiologia e Sono, Hospital de Clínicas de Porto Alegre (HCPA), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Fernanda Sbaraini Bonatto
- Laboratório de Cronobiologia e Sono, Hospital de Clínicas de Porto Alegre (HCPA), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
- Graduate Program in Psychiatry and Behavioral Sciences, School of Medicine, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Maria Paz Hidalgo
- Laboratório de Cronobiologia e Sono, Hospital de Clínicas de Porto Alegre (HCPA), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
- Graduate Program in Psychiatry and Behavioral Sciences, School of Medicine, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
- School of Medicine, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
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6
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Woelders T, Allen AE, Lucas RJ. Melanopsin enhances image persistence. Curr Biol 2023; 33:5048-5056.e4. [PMID: 37967553 DOI: 10.1016/j.cub.2023.10.039] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 09/28/2023] [Accepted: 10/20/2023] [Indexed: 11/17/2023]
Abstract
Contributions of the inner retinal photopigment melanopsin to human visual perception are incompletely understood. Here, we use a four-primary display to produce stimuli differing in melanopsin versus cone contrast in psychophysical paradigms in eight subjects with normal color vision. We address two predictions from electrophysiological recordings of the melanopsin system in non-human mammals: melanopsin influences color and/or supports image persistence under visual fixation. We first construct chromatic contrast sensitivity contours for stimuli differing in melanopsin excitation presented as a central annulus (10°) or peripheral (22.5°) spot. We find that although including melanopsin contrast produces modest changes in the average chromatic coordinates in both eccentricities, this occurs equally at low (0.5 Hz) and higher (3.75 Hz) temporal frequencies, arguing that it reflects divergence in cone spectral sensitivity in our participants from that captured in standardized cone fundamentals rather than a melanopsin contribution to color. We continue to ask whether the established ability of melanopsin to sustain firing of visual neurons under extended light exposure has a visual correlate, using the optical illusion of Troxler fading in which blurred spots in periphery disappear during visual fixation. We find that introducing additional melanopsin contrast (+28% Michelson contrast) to either bright or dark spots increases fading latency by 35% ± 8.8% and 41% ± 13.6%, respectively. Our data argue that the primary contribution of melanopsin to perception under these conditions is not to provide a color percept but rather to enhance persistence of low spatial frequency patterns during visual fixation.
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Affiliation(s)
- Tom Woelders
- Division of Neuroscience and Centre for Biological Timing, School of Biology, Faculty of Biology Medicine and Health, University of Manchester, Upper Brook Street, M13 9PT Manchester, UK.
| | - Annette E Allen
- Division of Neuroscience and Centre for Biological Timing, School of Biology, Faculty of Biology Medicine and Health, University of Manchester, Upper Brook Street, M13 9PT Manchester, UK
| | - Robert J Lucas
- Division of Neuroscience and Centre for Biological Timing, School of Biology, Faculty of Biology Medicine and Health, University of Manchester, Upper Brook Street, M13 9PT Manchester, UK.
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7
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Schöllhorn I, Stefani O, Blume C, Cajochen C. Seasonal Variation in the Responsiveness of the Melanopsin System to Evening Light: Why We Should Report Season When Collecting Data in Human Sleep and Circadian Studies. Clocks Sleep 2023; 5:651-666. [PMID: 37987395 PMCID: PMC10660855 DOI: 10.3390/clockssleep5040044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 09/07/2023] [Accepted: 10/09/2023] [Indexed: 11/22/2023] Open
Abstract
It is well known that variations in light exposure during the day affect light sensitivity in the evening. More daylight reduces sensitivity, and less daylight increases it. On average days, we spend less time outdoors in winter and receive far less light than in summer. Therefore, it could be relevant when collecting research data on the non-image forming (NIF) effects of light on circadian rhythms and sleep. In fact, studies conducted only in winter may result in more pronounced NIF effects than in summer. Here, we systematically collected information on the extent to which studies on the NIF effects of evening light include information on season and/or light history. We found that more studies were conducted in winter than in summer and that reporting when a study was conducted or measuring individual light history is not currently a standard in sleep and circadian research. In addition, we sought to evaluate seasonal variations in a previously published dataset of 72 participants investigating circadian and sleep effects of evening light exposure in a laboratory protocol where daytime light history was not controlled. In this study, we selectively modulated melanopic irradiance at four different light levels (<90 lx). Here, we aimed to retrospectively evaluate seasonal variations in the responsiveness of the melanopsin system by combining all data sets in an exploratory manner. Our analyses suggest that light sensitivity is indeed reduced in summer compared to winter. Thus, to increase the reproducibility of NIF effects on sleep and circadian measures, we recommend an assessment of the light history and encourage standardization of reporting guidelines on the seasonal distribution of measurements.
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Affiliation(s)
- Isabel Schöllhorn
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, 4002 Basel, Switzerland; (I.S.); (O.S.)
- Research Cluster Molecular and Cognitive Neurosciences (MCN), University of Basel, 4001 Basel, Switzerland
| | - Oliver Stefani
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, 4002 Basel, Switzerland; (I.S.); (O.S.)
- Research Cluster Molecular and Cognitive Neurosciences (MCN), University of Basel, 4001 Basel, Switzerland
- Lucerne University of Applied Sciences and Arts, Engineering and Architecture, Technikumstrasse 21, 6048 Horw, Switzerland
| | - Christine Blume
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, 4002 Basel, Switzerland; (I.S.); (O.S.)
- Research Cluster Molecular and Cognitive Neurosciences (MCN), University of Basel, 4001 Basel, Switzerland
- Department of Biomedicine, University of Basel, 4001 Basel, Switzerland
| | - Christian Cajochen
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, 4002 Basel, Switzerland; (I.S.); (O.S.)
- Research Cluster Molecular and Cognitive Neurosciences (MCN), University of Basel, 4001 Basel, Switzerland
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Martin JT, Boynton GM, Baker DH, Wade AR, Spitschan M. PySilSub: An open-source Python toolbox for implementing the method of silent substitution in vision and nonvisual photoreception research. J Vis 2023; 23:10. [PMID: 37450287 DOI: 10.1167/jov.23.7.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2023] Open
Abstract
The normal human retina contains several classes of photosensitive cell-rods for low-light vision, three cone classes for daylight vision, and intrinsically photosensitive retinal ganglion cells (ipRGCs) expressing melanopsin for non-image-forming functions, including pupil control, melatonin suppression, and circadian photoentrainment. The spectral sensitivities of the photoreceptors overlap significantly, which means that most lights will stimulate all photoreceptors to varying degrees. The method of silent substitution is a powerful tool for stimulating individual photoreceptor classes selectively and has found much use in research and clinical settings. The main hardware requirement for silent substitution is a spectrally calibrated light stimulation system with at least as many primaries as there are photoreceptors under consideration. Device settings that will produce lights to selectively stimulate the photoreceptor(s) of interest can be found using a variety of analytic and algorithmic approaches. Here we present PySilSub (https://github.com/PySilentSubstitution/pysilsub), a novel Python package for silent substitution featuring flexible support for individual colorimetric observer models (including human and mouse observers), multiprimary stimulation devices, and solving silent substitution problems with linear algebra and constrained numerical optimization. The toolbox is registered with the Python Package Index and includes example data sets from various multiprimary systems. We hope that PySilSub will facilitate the application of silent substitution in research and clinical settings.
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Affiliation(s)
- Joel T Martin
- Department of Psychology, University of York, York, UK
| | | | - Daniel H Baker
- Department of Psychology, University of York, York, UK
- York Biomedical Research Institute, University of York, York, UK
| | - Alex R Wade
- Department of Psychology, University of York, York, UK
- York Biomedical Research Institute, University of York, York, UK
| | - Manuel Spitschan
- Max Planck Institute for Biological Cybernetics, Tübingen, Germany
- TUM Department of Sport and Health Sciences (TUM SG), Technical University of Munich, Munich, Germany
- TUM Institute for Advanced Study (TUM-IAS), Technical University of Munich, Garching, Germany
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9
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Wolffsohn JS, Lingham G, Downie LE, Huntjens B, Inomata T, Jivraj S, Kobia-Acquah E, Muntz A, Mohamed-Noriega K, Plainis S, Read M, Sayegh RR, Singh S, Utheim TP, Craig JP. TFOS Lifestyle: Impact of the digital environment on the ocular surface. Ocul Surf 2023; 28:213-252. [PMID: 37062428 DOI: 10.1016/j.jtos.2023.04.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 04/06/2023] [Indexed: 04/18/2023]
Abstract
Eye strain when performing tasks reliant on a digital environment can cause discomfort, affecting productivity and quality of life. Digital eye strain (the preferred terminology) was defined as "the development or exacerbation of recurrent ocular symptoms and/or signs related specifically to digital device screen viewing". Digital eye strain prevalence of up to 97% has been reported, due to no previously agreed definition/diagnostic criteria and limitations of current questionnaires which fail to differentiate such symptoms from those arising from non-digital tasks. Objective signs such as blink rate or critical flicker frequency changes are not 'diagnostic' of digital eye strain nor validated as sensitive. The mechanisms attributed to ocular surface disease exacerbation are mainly reduced blink rate and completeness, partial/uncorrected refractive error and/or underlying binocular vision anomalies, together with the cognitive demand of the task and differences in position, size, brightness and glare compared to an equivalent non-digital task. In general, interventions are not well established; patients experiencing digital eye strain should be provided with a full refractive correction for the appropriate working distances. Improving blinking, optimizing the work environment and encouraging regular breaks may help. Based on current, best evidence, blue-light blocking interventions do not appear to be an effective management strategy. More and larger clinical trials are needed to assess artificial tear effectiveness for relieving digital eye strain, particularly comparing different constituents; a systematic review within the report identified use of secretagogues and warm compress/humidity goggles/ambient humidifiers as promising strategies, along with nutritional supplementation (such as omega-3 fatty acid supplementation and berry extracts).
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Affiliation(s)
- James S Wolffsohn
- College of Health & Life Sciences, School of Optometry, Aston University, Birmingham, UK; Department of Ophthalmology, New Zealand National Eye Centre, The University of Auckland, Auckland, New Zealand.
| | - Gareth Lingham
- Centre for Eye Research Ireland, Technological University Dublin, Dublin, Ireland
| | - Laura E Downie
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Byki Huntjens
- Division of Optometry and Visual Sciences, City, University of London, EC1V 0HB, UK
| | - Takenori Inomata
- Department of Ophthalmology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Saleel Jivraj
- College of Health & Life Sciences, School of Optometry, Aston University, Birmingham, UK
| | | | - Alex Muntz
- Department of Ophthalmology, New Zealand National Eye Centre, The University of Auckland, Auckland, New Zealand
| | - Karim Mohamed-Noriega
- Department of Ophthalmology, University Hospital and Faculty of Medicine, Autonomous University of Nuevo León (UANL). Monterrey, 64460, Mexico
| | - Sotiris Plainis
- College of Health & Life Sciences, School of Optometry, Aston University, Birmingham, UK; Laboratory of Optics and Vision, School of Medicine, University of Crete, Greece
| | - Michael Read
- Division of Pharmacy and Optometry, The University of Manchester, Manchester, UK
| | - Rony R Sayegh
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Sumeer Singh
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Tor P Utheim
- Department of Ophthalmology, Oslo University Hospital, Oslo, Norway
| | - Jennifer P Craig
- College of Health & Life Sciences, School of Optometry, Aston University, Birmingham, UK; Department of Ophthalmology, New Zealand National Eye Centre, The University of Auckland, Auckland, New Zealand
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10
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Schöllhorn I, Stefani O, Lucas RJ, Spitschan M, Slawik HC, Cajochen C. Melanopic irradiance defines the impact of evening display light on sleep latency, melatonin and alertness. Commun Biol 2023; 6:228. [PMID: 36854795 PMCID: PMC9974389 DOI: 10.1038/s42003-023-04598-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 02/15/2023] [Indexed: 03/02/2023] Open
Abstract
Evening light-emitting visual displays may disrupt sleep, suppress melatonin and increase alertness. Here, we control melanopic irradiance independent of display luminance and colour, in 72 healthy males 4 h before habitual bedtime and expose each of them to one of four luminance levels (i.e., dim light, smartphone, tablet or computer screen illuminance) at a low and a high melanopic irradiance setting. Low melanopic light shortens the time to fall asleep, attenuates evening melatonin suppression, reduces morning melatonin, advances evening melatonin onset and decreases alertness compared to high melanopic light. In addition, we observe dose-dependent increases in sleep latency, reductions in melatonin concentration and delays in melatonin onset as a function of melanopic irradiance-not so for subjective alertness. We identify melanopic irradiance as an appropriate parameter to mitigate the unwanted effects of screen use at night. Our results may help the many people who sit in front of screens in the evening or at night to fall asleep faster, feel sleepier, and have a more stable melatonin phase by spectrally tuning the visual display light without compromising the visual appearance.
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Affiliation(s)
- Isabel Schöllhorn
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland
- Research Platform Molecular and Cognitive Neurosciences (MCN), University of Basel, Basel, Switzerland
| | - Oliver Stefani
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland
- Research Platform Molecular and Cognitive Neurosciences (MCN), University of Basel, Basel, Switzerland
| | - Robert J Lucas
- Centre for Biological Timing, Division of Neuroscience, School of Biological Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
| | - Manuel Spitschan
- Translational Sensory & Circadian Neuroscience, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
- Chronobiology & Health, TUM Department of Sport and Health Sciences (TUM SG), Technical University of Munich, Munich, Germany
- TUM Institute for Advanced Study (TUM-IAS), Technical University of Munich, Garching, Germany
| | - Helen C Slawik
- Clinical Sleep Laboratory, Psychiatric Hospital of the University of Basel, Basel, Switzerland
| | - Christian Cajochen
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland.
- Research Platform Molecular and Cognitive Neurosciences (MCN), University of Basel, Basel, Switzerland.
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11
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Melatonin: Both a Messenger of Darkness and a Participant in the Cellular Actions of Non-Visible Solar Radiation of Near Infrared Light. BIOLOGY 2023; 12:biology12010089. [PMID: 36671781 PMCID: PMC9855654 DOI: 10.3390/biology12010089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 12/25/2022] [Accepted: 01/04/2023] [Indexed: 01/07/2023]
Abstract
Throughout the history of melatonin research, almost exclusive focus has been on nocturnally-generated pineal melatonin production, which accounts for its circadian rhythm in the blood and cerebrospinal fluid; these light/dark melatonin cycles drive the daily and seasonal photoperiodic alterations in organismal physiology. Because pineal melatonin is produced and secreted primarily at night, it is referred to as the chemical expression of darkness. The importance of the other sources of melatonin has almost been ignored. Based on current evidence, there are at least four sources of melatonin in vertebrates that contribute to the whole-body melatonin pool. These include melatonin produced by (1) the pineal gland; (2) extrapineal cells, tissues, and organs; (3) the microbiota of the skin, mouth, nose, digestive tract, and vagina as well as (4) melatonin present in the diet. These multiple sources of melatonin exhibit differentially regulated mechanisms for its synthesis. Visible light striking the retina or an intense physical stimulus can suppress nocturnal pineal melatonin levels; in contrast, there are examples where extrapineal melatonin levels are increased during heavy exercise in daylight, which contains the whole range of NIR radiation. The cumulative impact of all cells producing augmented extrapineal melatonin is sufficient to elevate sweat concentrations, and potentially, if the exposure is sustained, to also increasing the circulating values. The transient increases in sweat and plasma melatonin support the premise that extrapineal melatonin has a production capacity that exceeds by far what can be produced by the pineal gland, and is used to maintain intercellular homeostasis and responds to rapid changes in ROS density. The potential regulatory mechanisms of near infrared light (NIR) on melatonin synthesis are discussed in detail herein. Combined with the discovery of high levels of melanopsin in most fat cells and their response to light further calls into question pineal centric theories. While the regulatory processes related to microbiota-derived melatonin are currently unknown, there does seem to be crosstalk between melatonin derived from the host and that originating from microbiota.
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12
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Blume C, Niedernhuber M, Spitschan M, Slawik HC, Meyer MP, Bekinschtein TA, Cajochen C. Melatonin suppression does not automatically alter sleepiness, vigilance, sensory processing, or sleep. Sleep 2022; 45:zsac199. [PMID: 35998110 PMCID: PMC9644120 DOI: 10.1093/sleep/zsac199] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 08/02/2022] [Indexed: 09/19/2023] Open
Abstract
Presleep exposure to short-wavelength light suppresses melatonin and decreases sleepiness with activating effects extending to sleep. This has mainly been attributed to melanopic effects, but mechanistic insights are missing. Thus, we investigated whether two light conditions only differing in the melanopic effects (123 vs. 59 lx melanopic EDI) differentially affect sleep besides melatonin. Additionally, we studied whether the light differentially modulates sensory processing during wakefulness and sleep. Twenty-nine healthy volunteers (18-30 years, 15 women) were exposed to two metameric light conditions (high- vs. low-melanopic, ≈60 photopic lx) for 1 h ending 50 min prior to habitual bed time. This was followed by an 8-h sleep opportunity with polysomnography. Objective sleep measurements were complemented by self-report. Salivary melatonin, subjective sleepiness, and behavioral vigilance were sampled at regular intervals. Sensory processing was evaluated during light exposure and sleep on the basis of neural responses related to violations of expectations in an oddball paradigm. We observed suppression of melatonin by ≈14% in the high- compared to the low-melanopic condition. However, conditions did not differentially affect sleep, sleep quality, sleepiness, or vigilance. A neural mismatch response was evident during all sleep stages, but not differentially modulated by light. Suppression of melatonin by light targeting the melanopic system does not automatically translate to acutely altered levels of vigilance or sleepiness or to changes in sleep, sleep quality, or basic sensory processing. Given contradicting earlier findings and the retinal anatomy, this may suggest that an interaction between melanopsin and cone-rod signals needs to be considered. Clinical Trial Registry: German Clinical Trials Register, DRKS00023602, https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00023602.
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Affiliation(s)
- Christine Blume
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland (institution, where the work was performed)
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland
| | - Maria Niedernhuber
- Consciousness and Cognition Lab, Department of Psychology, University of Cambridge, Cambridge, UK
| | - Manuel Spitschan
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland (institution, where the work was performed)
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland
- Translational Sensory and Circadian Neuroscience, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
- TUM Department of Sport and Health Sciences (TUM SG), Technical University of Munich, Munich, Germany
| | - Helen C Slawik
- Psychiatric Hospital of the University of Basel, Basel, Switzerland
| | - Martin P Meyer
- Psychiatric Hospital of the University of Basel, Basel, Switzerland
| | - Tristan A Bekinschtein
- Consciousness and Cognition Lab, Department of Psychology, University of Cambridge, Cambridge, UK
| | - Christian Cajochen
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland (institution, where the work was performed)
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland
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13
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Spitschan M, Mead J, Roos C, Lowis C, Griffiths B, Mucur P, Herf M, Nam S, Veitch JA. luox: validated reference open-access and open-source web platform for calculating and sharing physiologically relevant quantities for light and lighting. Wellcome Open Res 2022; 6:69. [PMID: 34017925 PMCID: PMC8095192 DOI: 10.12688/wellcomeopenres.16595.3] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/06/2022] [Indexed: 11/22/2023] Open
Abstract
Light exposure has a profound impact on human physiology and behaviour. For example, light exposure at the wrong time can disrupt our circadian rhythms and acutely suppress the production of melatonin. In turn, appropriately timed light exposure can support circadian photoentrainment. Beginning with the discovery that melatonin production is acutely suppressed by bright light more than 40 years ago, understanding which aspects of light drive the 'non-visual' responses to light remains a highly active research area, with an important translational dimension and implications for "human-centric" or physiologically inspired architectural lighting design. In 2018, the International Commission on Illumination (CIE) standardised the spectral sensitivities for predicting the non-visual effects of a given spectrum of light with respect to the activation of the five photoreceptor classes in the human retina: the L, M and S cones, the rods, and the melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs). Here, we described a novel, lean, user-friendly, open-access and open-source platform for calculating quantities related to light. The platform, called luox, enables researchers and research users in vision science, lighting research, chronobiology, sleep research and adjacent fields to turn spectral measurements into reportable quantities. The luox code base, released under the GPL-3.0 License, is modular and therefore extendable to other spectrum-derived quantities. luox calculations of CIE quantities and indices have been endorsed by the CIE following black-box validation.
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Affiliation(s)
- Manuel Spitschan
- Department of Experimental Psychology, University of Oxford, Oxford, UK
- Sleep and Circadian Neuroscience Institute (SCNi), University of Oxford, Oxford, UK
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland
- TUM Department of Sport and Health Sciences (TUM SG), Chronobiology & Health, Technical University of Munich, Munich, Germany
- Max Planck Institute for Biological Cybernetics, Translational Sensory & Circadian Neuroscience, Tübingen, Germany
- TUM Institute for Advanced Study (TUM-IAS), Technical University of Munich, Garching, Germany
| | | | | | | | | | | | | | - Somang Nam
- National Research Council of Canada, Construction Research Centre, Ottawa, Canada
| | - Jennifer A. Veitch
- National Research Council of Canada, Construction Research Centre, Ottawa, Canada
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14
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Brown TM, Brainard GC, Cajochen C, Czeisler CA, Hanifin JP, Lockley SW, Lucas RJ, Münch M, O’Hagan JB, Peirson SN, Price LLA, Roenneberg T, Schlangen LJM, Skene DJ, Spitschan M, Vetter C, Zee PC, Wright KP. Recommendations for daytime, evening, and nighttime indoor light exposure to best support physiology, sleep, and wakefulness in healthy adults. PLoS Biol 2022; 20:e3001571. [PMID: 35298459 PMCID: PMC8929548 DOI: 10.1371/journal.pbio.3001571] [Citation(s) in RCA: 79] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Ocular light exposure has important influences on human health and well-being through modulation of circadian rhythms and sleep, as well as neuroendocrine and cognitive functions. Prevailing patterns of light exposure do not optimally engage these actions for many individuals, but advances in our understanding of the underpinning mechanisms and emerging lighting technologies now present opportunities to adjust lighting to promote optimal physical and mental health and performance. A newly developed, international standard provides a SI-compliant way of quantifying the influence of light on the intrinsically photosensitive, melanopsin-expressing, retinal neurons that mediate these effects. The present report provides recommendations for lighting, based on an expert scientific consensus and expressed in an easily measured quantity (melanopic equivalent daylight illuminance (melaponic EDI)) defined within this standard. The recommendations are supported by detailed analysis of the sensitivity of human circadian, neuroendocrine, and alerting responses to ocular light and provide a straightforward framework to inform lighting design and practice.
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Affiliation(s)
- Timothy M. Brown
- Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
- * E-mail: (TMB); (KPW)
| | - George C. Brainard
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Christian Cajochen
- Centre for Chronobiology, University Psychiatric Clinics Basel, Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland
| | - Charles A. Czeisler
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
| | - John P. Hanifin
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Steven W. Lockley
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
- Surrey Sleep Research Centre, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Robert J. Lucas
- Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Mirjam Münch
- Centre for Chronobiology, University Psychiatric Clinics Basel, Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland
- Research Centre for Hauora and Health, Massey University, Wellington, New Zealand
| | - John B. O’Hagan
- Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Chilton, Didcot, United Kingdom
| | - Stuart N. Peirson
- Sleep and Circadian Neuroscience Institute, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Luke L. A. Price
- Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Chilton, Didcot, United Kingdom
| | - Till Roenneberg
- Institutes for Medical Psychology and Occupational, Social and Environmental Medicine, Medical Faculty, Ludwig-Maximilians University (LMU), Munich, Germany
| | - Luc J. M. Schlangen
- Human Technology Interaction Group, Department of Industrial Engineering and Innovation Sciences, Eindhoven University of Technology, Eindhoven, the Netherlands
- Intelligent Lighting Institute, Eindhoven University of Technology, Eindhoven, the Netherlands
| | - Debra J. Skene
- Chronobiology, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Manuel Spitschan
- Translational Sensory & Circadian Neuroscience, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
- TUM Department of Sport and Health Sciences (TUM SG), Technical University of Munich, Munich, Germany
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Céline Vetter
- Circadian and Sleep Epidemiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States of America
| | - Phyllis C. Zee
- Department of Neurology, Northwestern University, Chicago, Illinois, United States of America
- Center for Circadian and Sleep Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Kenneth P. Wright
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States of America
- * E-mail: (TMB); (KPW)
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15
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Hou D, Lin C, Lin Y. Diurnal Circadian Lighting Accumulation Model: A Predictor of the Human Circadian Phase Shift Phenotype. PHENOMICS (CHAM, SWITZERLAND) 2022; 2:50-63. [PMID: 36939753 PMCID: PMC9590583 DOI: 10.1007/s43657-021-00039-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 12/08/2021] [Accepted: 12/10/2021] [Indexed: 11/15/2022]
Abstract
Light is an important external factor that affects human circadian rhythms. This study aimed to explore the effects of different dimensions of diurnal light exposure on the physiological circadian phase shift (CPS) of the human body. A strict light exposure experiment with different timing schemes (8:00-12:00, 13:00-17:00, 18:00-22:00), durations (4 h, 8 h) and effective circadian stimulus levels (circadian stimulus: 0.35, 0.55) was performed in an enclosed laboratory. Fourteen participants, including seven males and seven females, with a mean age of 24.29 ± 2.43 (mean ± standard deviation), participated in this experiment and experienced all six lighting schemes. The results showed that both time factor (F 3,40 = 29.079, p < 0.001, the power of the sample size = 0.98) and circadian stimulus levels (T 20 = - 2.415, p = 0.025, the power of sample size = 0.76) significantly affect the CPS. On this basis, a diurnal circadian lighting accumulation (DCLA)-CPS model was proposed in the form of the Boltzmann function, and was validated by experimental data with high correlation (R 2 = 0.9320, RSS = 0.1184), which provides strong support for rationally arranging the light level at different times of the day.
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Affiliation(s)
- Dandan Hou
- grid.8547.e0000 0001 0125 2443Institute for Electric Light Sources, School of Information Science and Technology, Fudan University, Shanghai, 200438 China
- grid.8547.e0000 0001 0125 2443Institute of Future Lighting, Academy for Engineering and Technology, Fudan University, Shanghai, 200433 China
- grid.8547.e0000 0001 0125 2443Human Phenome Institute, Fudan University, Shanghai, 201203 China
| | - Caixin Lin
- grid.8547.e0000 0001 0125 2443Institute for Electric Light Sources, School of Information Science and Technology, Fudan University, Shanghai, 200438 China
| | - Yandan Lin
- grid.8547.e0000 0001 0125 2443Institute for Electric Light Sources, School of Information Science and Technology, Fudan University, Shanghai, 200438 China
- grid.8547.e0000 0001 0125 2443Human Phenome Institute, Fudan University, Shanghai, 201203 China
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16
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Pohanka M. New uses of Melatonin as a Drug, a Review. Curr Med Chem 2022; 29:3622-3637. [PMID: 34986763 DOI: 10.2174/0929867329666220105115755] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 10/25/2021] [Accepted: 11/21/2021] [Indexed: 11/22/2022]
Abstract
Melatonin is a simple compound with a proper chemical name N-acetyl-5-methoxy tryptamine and known as a hormone controlling circadian rhythm. Humans produce melatonin at night which is the reason for sleeping in the night and awakening over the day. Melatonin interacts with melatonin receptors MT1 and MT2 but it was also revealed that melatonin is a strong antioxidant and it also has a role in regulation of cell cycle. Currently, melatonin is used as a drug for some types of sleep disorder but the recent research points to the fact that melatonin can also serve for the other purposes including prophylaxis or therapy of lifestyle diseases, cancer, neurodegenerative disorders and exposure to chemicals. This review summarizes basic facts and direction of the current research on melatonin. The actual literature was scrutinized for the purpose of this review.
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Affiliation(s)
- Miroslav Pohanka
- Faculty of Military Health Sciences, University of Defense, Trebesska 1575, Hradec Kralove CZ-50001, Czech Republic
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17
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Zandi B, Stefani O, Herzog A, Schlangen LJM, Trinh QV, Khanh TQ. Optimising metameric spectra for integrative lighting to modulate the circadian system without affecting visual appearance. Sci Rep 2021; 11:23188. [PMID: 34848762 PMCID: PMC8633386 DOI: 10.1038/s41598-021-02136-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 11/10/2021] [Indexed: 01/15/2023] Open
Abstract
Smart integrative lighting systems aim to support human health and wellbeing by capitalising on the light-induced effects on circadian rhythms, sleep, and cognitive functions, while optimising the light's visual aspects like colour fidelity, visual comfort, visual preference, and visibility. Metameric spectral tuning could be an instrument to solve potential conflicts between the visual preferences of users with respect to illuminance and chromaticity and the circadian consequences of the light exposure, as metamers can selectively modulate melanopsin-based photoreception without affecting visual properties such as chromaticity or illuminance. This work uses a 6-, 8- and 11-channel LED luminaire with fixed illuminance of 250 lx to systematically investigate the metameric tuning range in melanopic equivalent daylight illuminance (EDI) and melanopic daylight efficacy ratio (melanopic DER) for 561 chromaticity coordinates as optimisation targets (2700 K to 7443 K ± Duv 0 to 0.048), while applying colour fidelity index Rf criteria from the TM-30-20 Annex E recommendations (i.e. Rf [Formula: see text] 85, Rf,h1 [Formula: see text] 85). Our results reveal that the melanopic tuning range increases with rising CCT to a maximum tuning range in melanopic DER of 0.24 (CCT: 6702 K, Duv: 0.003), 0.29 (CCT: 7443 K, Duv: 0) and 0.30 (CCT: 6702, Duv: 0.006), depending on the luminaire's channel number of 6, 8 or 11, respectively. This allows to vary the melanopic EDI from 212.5-227.5 lx up to 275-300 lx without changes in the photopic illuminance (250 lx) or chromaticity ([Formula: see text] [Formula: see text] 0.0014). The highest metameric melanopic Michelson contrast for the 6-, 8- and 11-channel luminaire is 0.16, 0.18 and 0.18, which is accomplished at a CCT of 3017 K (Duv: - 0.018), 3456 K (Duv: 0.009) and 3456 K (Duv: 0.009), respectively. By optimising ~ 490,000 multi-channel LED spectra, we identified chromaticity regions in the CIExy colour space that are of particular interest to control the melanopic efficacy with metameric spectral tuning.
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Affiliation(s)
- Babak Zandi
- Department of Electrical Engineering and Information Technology, Laboratory of Lighting Technology, Technical University of Darmstadt, Darmstadt, Germany.
| | - Oliver Stefani
- Transfaculty Research Platform Molecular and Cognitive Neurosciences (MCN), Centre for Chronobiology, University of Basel, Basel, Switzerland
| | - Alexander Herzog
- Department of Electrical Engineering and Information Technology, Laboratory of Lighting Technology, Technical University of Darmstadt, Darmstadt, Germany
| | - Luc J M Schlangen
- Department Human-Technology, Intelligent Lighting Institute, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Quang Vinh Trinh
- Department of Electrical Engineering and Information Technology, Laboratory of Lighting Technology, Technical University of Darmstadt, Darmstadt, Germany
| | - Tran Quoc Khanh
- Department of Electrical Engineering and Information Technology, Laboratory of Lighting Technology, Technical University of Darmstadt, Darmstadt, Germany
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18
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Arguelles-Prieto R, Madrid JA, Rol MA, Bonmati-Carrion MA. Correlated color temperature and light intensity: Complementary features in non-visual light field. PLoS One 2021; 16:e0254171. [PMID: 34252130 PMCID: PMC8274909 DOI: 10.1371/journal.pone.0254171] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 06/22/2021] [Indexed: 02/05/2023] Open
Abstract
An appropriate exposure to the light-dark cycle, with high irradiances during the day and darkness during the night is essential to keep our physiology on time. However, considering the increasing exposure to artificial light at night and its potential harmful effects on health (i.e. chronodisruption and associated health conditions), it is essential to understand the non-visual effects of light in humans. Melatonin suppression is considered the gold standard for nocturnal light effects, and the activation of intrinsically photosensitive retinal ganglion cells (ipRGCs) through the assessment of pupillary light reflex (PLR) has been recently gaining attention. Also, some theoretical models for melatonin suppression and retinal photoreceptors activation have been proposed. Our aim in this study was to determine the influence of correlated color temperature (CCT) on melatonin suppression and PLR, considering two commercial light sources, as well as to explore the possible correlation between both processes. Also, the contribution of irradiance (associated to CCT) was explored through mathematical modelling on a wider range of light sources. For that, melatonin suppression and PLR were experimentally assessed on 16 healthy and young volunteers under two light conditions (warmer, CCT 3000 K; and cooler, CCT 5700 K, at ~5·1018 photons/cm2/sec). Our experimental results yielded greater post-stimulus constriction under the cooler (5700 K, 13.3 ± 1.9%) than under the warmer light (3000 K, 8.7 ± 1.2%) (p < 0.01), although no significant differences were found between both conditions in terms of melatonin suppression. Interestingly, we failed to demonstrate correlation between PLR and melatonin suppression. Although methodological limitations cannot be discarded, this could be due to the existence of different subpopulations of Type 1 ipRGCs differentially contributing to PLR and melatonin suppression, which opens the way for further research on ipRGCs projection in humans. The application of theoretical modelling suggested that CCT should not be considered separately from irradiance when designing nocturnal/diurnal illumination systems. Further experimental studies on wider ranges of CCTs and light intensities are needed to confirm these conclusions.
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Affiliation(s)
- Raquel Arguelles-Prieto
- Chronobiology Lab, Department of Physiology, College of Biology, University of Murcia, Mare Nostrum Campus, IUIE, IMIB-Arrixaca, Murcia, Spain
| | - Juan Antonio Madrid
- Chronobiology Lab, Department of Physiology, College of Biology, University of Murcia, Mare Nostrum Campus, IUIE, IMIB-Arrixaca, Murcia, Spain
- Ciber Fragilidad y Envejecimiento Saludable (CIBERFES), Madrid, Spain
| | - Maria Angeles Rol
- Chronobiology Lab, Department of Physiology, College of Biology, University of Murcia, Mare Nostrum Campus, IUIE, IMIB-Arrixaca, Murcia, Spain
- Ciber Fragilidad y Envejecimiento Saludable (CIBERFES), Madrid, Spain
| | - Maria Angeles Bonmati-Carrion
- Chronobiology Lab, Department of Physiology, College of Biology, University of Murcia, Mare Nostrum Campus, IUIE, IMIB-Arrixaca, Murcia, Spain
- Ciber Fragilidad y Envejecimiento Saludable (CIBERFES), Madrid, Spain
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19
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Spitschan M, Mead J, Roos C, Lowis C, Griffiths B, Mucur P, Herf M. luox: novel validated open-access and open-source web platform for calculating and sharing physiologically relevant quantities for light and lighting. Wellcome Open Res 2021; 6:69. [PMID: 34017925 PMCID: PMC8095192 DOI: 10.12688/wellcomeopenres.16595.2] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/01/2021] [Indexed: 12/16/2022] Open
Abstract
Light exposure has a profound impact on human physiology and behaviour. For example, light exposure at the wrong time can disrupt our circadian rhythms and acutely suppress the production of melatonin. In turn, appropriately timed light exposure can support circadian photoentrainment. Beginning with the discovery that melatonin production is acutely suppressed by bright light more than 40 years ago, understanding which aspects of light drive the 'non-visual' responses to light remains a highly active research area, with an important translational dimension and implications for "human-centric" or physiologically inspired architectural lighting design. In 2018, the International Commission on Illumination (CIE) standardised the spectral sensitivities for predicting the non-visual effects of a given spectrum of light with respect to the activation of the five photoreceptor classes in the human retina: the L, M and S cones, the rods, and the melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs). Here, we described a novel, lean, user-friendly, open-access and open-source platform for calculating quantities related to light. The platform, called luox, enables researchers and research users in chronobiology, sleep research and adjacent field to turn spectral measurements into reportable quantities. The luox code base, released under the GPL-3.0 License, is modular and therefore extendable to other spectrum-derived quantities. luox has been endorsed by the CIE following black-box validation.
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Affiliation(s)
- Manuel Spitschan
- Department of Experimental Psychology, University of Oxford, Oxford, UK.,Sleep and Circadian Neuroscience Institute (SCNi), University of Oxford, Oxford, UK.,Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland.,Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland
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20
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Mouland JW, Martial FP, Lucas RJ, Brown TM. Modulations in irradiance directed at melanopsin, but not cone photoreceptors, reliably alter electrophysiological activity in the suprachiasmatic nucleus and circadian behaviour in mice. J Pineal Res 2021; 70:e12735. [PMID: 33793975 DOI: 10.1111/jpi.12735] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 03/23/2021] [Indexed: 12/25/2022]
Abstract
Intrinsically photosensitive retinal ganglion cells convey intrinsic, melanopsin-based, photoreceptive signals alongside those produced by rods and cones to the suprachiasmatic nucleus (SCN) circadian clock. To date, experimental data suggest that melanopsin plays a more significant role in measuring ambient light intensity than cone photoreception. Such studies have overwhelmingly used diffuse light stimuli, whereas light intensity in the world around us varies across space and time. Here, we investigated the extent to which melanopsin or cone signals support circadian irradiance measurements in the presence of naturalistic spatiotemporal variations in light intensity. To address this, we first presented high- and low-contrast movies to anaesthetised mice whilst recording extracellular electrophysiological activity from the SCN. Using a mouse line with altered cone sensitivity (Opn1mwR mice) and multispectral light sources we then selectively varied irradiance of the movies for specific photoreceptor classes. We found that steps in melanopic irradiance largely account for the light induced-changes in SCN activity over a range of starting light intensities and in the presence of spatiotemporal modulation. By contrast, cone-directed changes in irradiance only influenced SCN activity when spatiotemporal contrast was low. Consistent with these findings, under housing conditions where we could independently adjust irradiance for melanopsin versus cones, the period lengthening effects of constant light on circadian rhythms in behaviour were reliably determined by melanopic irradiance, regardless of irradiance for cones. These data add to the growing evidence that modulating effective irradiance for melanopsin is an effective strategy for controlling the circadian impact of light.
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Affiliation(s)
- Josh W Mouland
- Centre for Biological Timing, Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
- Division of Diabetes, Endocrinology and Gastroenterology, Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
| | - Franck P Martial
- Centre for Biological Timing, Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
- Division of Neuroscience and Experimental Psychology, Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
| | - Robert J Lucas
- Centre for Biological Timing, Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
- Division of Neuroscience and Experimental Psychology, Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
| | - Timothy M Brown
- Centre for Biological Timing, Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
- Division of Diabetes, Endocrinology and Gastroenterology, Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
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21
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Chellappa SL. Individual differences in light sensitivity affect sleep and circadian rhythms. Sleep 2021; 44:5922657. [PMID: 33049062 DOI: 10.1093/sleep/zsaa214] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 09/28/2020] [Indexed: 02/07/2023] Open
Abstract
Artificial lighting is omnipresent in contemporary society with disruptive consequences for human sleep and circadian rhythms because of overexposure to light, particularly in the evening/night hours. Recent evidence shows large individual variations in circadian photosensitivity, such as melatonin suppression, due to artificial light exposure. Despite the emerging body of research indicating that the effects of light on sleep and circadian rhythms vary dramatically across individuals, recommendations for appropriate light exposure in real-life settings rarely consider such individual effects. This review addresses recently identified links among individual traits, for example, age, sex, chronotype, genetic haplotypes, and the effects of evening/night light on sleep and circadian hallmarks, based on human laboratory and field studies. Target biological mechanisms for individual differences in light sensitivity include differences occurring within the retina and downstream, such as the central circadian clock. This review also highlights that there are wide gaps of uncertainty, despite the growing awareness that individual differences shape the effects of evening/night light on sleep and circadian physiology. These include (1) why do certain individual traits differentially affect the influence of light on sleep and circadian rhythms; (2) what is the translational value of individual differences in light sensitivity in populations typically exposed to light at night, such as night shift workers; and (3) what is the magnitude of individual differences in light sensitivity in population-based studies? Collectively, the current findings provide strong support for considering individual differences when defining optimal lighting specifications, thus allowing for personalized lighting solutions that promote quality of life and health.
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Affiliation(s)
- Sarah L Chellappa
- Medical Chronobiology Program, Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston, MA.,Division of Sleep Medicine, Department of Medicine, Harvard Medical School, Boston, MA
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22
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Spitschan M, Mead J, Roos C, Lowis C, Griffiths B, Mucur P, Herf M. luox: novel open-access and open-source web platform for calculating and sharing physiologically relevant quantities for light and lighting. Wellcome Open Res 2021; 6:69. [DOI: 10.12688/wellcomeopenres.16595.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/12/2021] [Indexed: 11/20/2022] Open
Abstract
Light exposure has a profound impact on human physiology and behaviour. For example, light exposure at the wrong time can disrupt our circadian rhythms and acutely suppress the production of melatonin. In turn, appropriately timed light exposure can support circadian photoentrainment. Beginning with the discovery that melatonin production is acutely suppressed by bright light more than 40 years ago, understanding which aspects of light drive the 'non-visual' responses to light remains a highly active research area, with an important translational dimension and implications for "human-centric" or physiologically inspired architectural lighting design. In 2018, the International Commission on Illumination (CIE) standardised the spectral sensitivities for predicting the non-visual effects of a given spectrum of light with respect to the activation of the five photoreceptor classes in the human retina: the L, M and S cones, the rods, and the melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs). Here, we described a novel, lean, user-friendly, open-access and open-source platform for calculating quantities related to light. The platform, called luox, enables researchers and research users in chronobiology, sleep research and adjacent field to turn spectral measurements into reportable quantities. The luox code base, released under the GPL-3.0 License, is modular and therefore extendable to other spectrum-derived quantities.
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23
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Schlangen LJM, Price LLA. The Lighting Environment, Its Metrology, and Non-visual Responses. Front Neurol 2021; 12:624861. [PMID: 33746879 PMCID: PMC7970181 DOI: 10.3389/fneur.2021.624861] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 02/04/2021] [Indexed: 12/11/2022] Open
Abstract
International standard CIE S 026:2018 provides lighting professionals and field researchers in chronobiology with a method to characterize light exposures with respect to non-visual photoreception and responses. This standard defines five spectral sensitivity functions that describe optical radiation for its ability to stimulate each of the five α-opic retinal photoreceptor classes that contribute to the non-visual effects of light in humans via intrinsically-photosensitive retinal ganglion cells (ipRGCs). The CIE also recently published an open-access α-opic toolbox that calculates all the quantities and ratios of the α-opic metrology in the photometric, radiometric and photon systems, based on either a measured (user-defined) spectrum or selected illuminants (A, D65, E, FL11, LED-B3) built into the toolbox. For a wide variety of ecologically-valid conditions, the melanopsin-based photoreception of ipRGCs has been shown to account for the spectral sensitivity of non-visual responses, from shifting the timing of nocturnal sleep and melatonin secretion to regulating steady-state pupil diameter. Recent findings continue to confirm that the photopigment melanopsin also plays a role in visual responses, and that melanopsin-based photoreception may have a significant influence on brightness perception and aspects of spatial vision. Although knowledge concerning the extent to which rods and cones interact with ipRGCs in driving non-visual effects is still growing, a CIE position statement recently used melanopic equivalent daylight (D65) illuminance in preliminary guidance on applying “proper light at the proper time” to manipulate non-visual responses. Further guidance on this approach is awaited from the participants of the 2nd International Workshop on Circadian and Neurophysiological Photometry (in Manchester, August 2019). The new α-opic metrology of CIE S 026 enables traceable measurements and a formal, quantitative specification of personal light exposures, photic interventions and lighting designs. Here, we apply this metrology to everyday light sources including a natural daylight time series, a range of LED lighting products and, using the toobox, to a smartphone display screen. This collection of examples suggests ways in which variations in the melanopic content of light over the day can be adopted in strategies that use light to support human health and well-being.
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Affiliation(s)
- Luc J M Schlangen
- Department Human-Technology Interaction, Intelligent Lighting Institute, Eindhoven University of Technology, Eindhoven, Netherlands
| | - Luke L A Price
- Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Didcot, United Kingdom
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24
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Comment Concerning the Effects of Light Intensity on Melatonin Suppression in the Review "Light Modulation of Human Clocks, Wake, and Sleep" by A. Prayag et al. Clocks Sleep 2021; 3:181-188. [PMID: 33578834 PMCID: PMC7931082 DOI: 10.3390/clockssleep3010011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 12/18/2020] [Indexed: 11/17/2022] Open
Abstract
Dose-response curves for circadian phase shift and melatonin suppression in relation to white or monochromatic nighttime illumination can be scaled to melanopic weighed illumination for normally constricted pupils, which makes them easier to interpret and compare. This is helpful for a practical applications.
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25
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Houser KW, Esposito T. Human-Centric Lighting: Foundational Considerations and a Five-Step Design Process. Front Neurol 2021; 12:630553. [PMID: 33584531 PMCID: PMC7873560 DOI: 10.3389/fneur.2021.630553] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 01/06/2021] [Indexed: 12/22/2022] Open
Abstract
At its best, human-centric lighting considers the visual and non-visual effects of light in support of positive human outcomes. At its worst, it is a marketing phrase used to healthwash lighting products or lighting design solutions. There is no doubt that environmental lighting contributes to human health, but how might one practice human-centric lighting given both the credible potential and the implausible hype? Marketing literature is filled with promises. Technical lighting societies have summarized the science but have not yet offered design guidance. Meanwhile, designers are in the middle, attempting to distinguish credible knowledge from that which is dubious to make design decisions that affect people directly. This article is intended to: (1) empower the reader with fundamental understandings of ways in which light affects health; (2) provide a process for human-centric lighting design that can dovetail with the decision-making process that is already a part of a designer's workflow.
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Affiliation(s)
- Kevin W. Houser
- School of Civil and Construction Engineering, Oregon State University, Corvallis, OR, United States
- Advanced Lighting Team, Pacific Northwest National Laboratory, Portland, OR, United States
| | - Tony Esposito
- Lighting Research Solutions LLC, Cambridge, MA, United States
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26
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Melanopic Limits of Metamer Spectral Optimisation in Multi-Channel Smart Lighting Systems. ENERGIES 2021. [DOI: 10.3390/en14030527] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Modern indoor lighting faces the challenge of finding an appropriate balance between energy consumption, legal requirements, visual performance, and the circadian effectiveness of a spectrum. Multi-channel LED luminaires have the option of keeping image-forming metrics steady while varying the melanopic radiance through metamer spectra for non-visual purposes. Here, we propose the theoretical concept of an automated smart lighting system that is designed to satisfy the user’s visual preference through neural networks while triggering the non-visual pathway via metamers. To quantify the melanopic limits of metamers at a steady chromaticity point, we have used 561 chromaticity coordinates along the Planckian locus (2700 K to 7443 K, ±Duv 0 to 0.048) as optimisation targets and generated the spectra by using a 6-channel, 8-channel, and 11-channel LED combination at three different luminance levels. We have found that in a best-case scenario, the melanopic radiance can be varied up to 65% while keeping the chromaticity coordinates constant (Δu′v′≤7.05×10−5) by using metamer spectra. The highest melanopic metamer contrast can be reached near the Planckian locus between 3292 and 4717 K within a Duv range of −0.009 to 0.006. Additionally, we publish over 1.2 million optimised spectra generated by multichannel LED luminaires as an open-source dataset along with this work.
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27
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Sunde E, Pedersen T, Mrdalj J, Thun E, Grønli J, Harris A, Bjorvatn B, Waage S, Skene DJ, Pallesen S. Alerting and Circadian Effects of Short-Wavelength vs. Long-Wavelength Narrow-Bandwidth Light during a Simulated Night Shift. Clocks Sleep 2020; 2:502-522. [PMID: 33255613 PMCID: PMC7712639 DOI: 10.3390/clockssleep2040037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 11/12/2020] [Accepted: 11/23/2020] [Indexed: 11/18/2022] Open
Abstract
Light can be used to facilitate alertness, task performance and circadian adaptation during night work. Novel strategies for illumination of workplaces, using ceiling mounted LED-luminaires, allow the use of a range of different light conditions, altering intensity and spectral composition. This study (ClinicalTrials.gov Identifier NCT03203538) investigated the effects of short-wavelength narrow-bandwidth light (λmax = 455 nm) compared to long-wavelength narrow-bandwidth light (λmax = 625 nm), with similar photon density (~2.8 × 1014 photons/cm2/s) across light conditions, during a simulated night shift (23:00–06:45 h) when conducting cognitive performance tasks. Light conditions were administered by ceiling mounted LED-luminaires. Using a within-subjects repeated measurements study design, a total of 34 healthy young adults (27 females and 7 males; mean age = 21.6 years, SD = 2.0 years) participated. The results revealed significantly reduced sleepiness and improved task performance during the night shift with short-wavelength light compared to long-wavelength light. There was also a larger shift of the melatonin rhythm (phase delay) after working a night shift in short-wavelength light compared to long-wavelength light. Participants’ visual comfort was rated as better in the short-wavelength light than the long-wavelength light. Ceiling mounted LED-luminaires may be feasible to use in real workplaces, as these have the potential to provide light conditions that are favorable for alertness and performance among night workers.
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Affiliation(s)
- Erlend Sunde
- Department of Psychosocial Science, Faculty of Psychology, University of Bergen, 5020 Bergen, Norway; (A.H.); (S.P.)
- Correspondence: ; Tel.: +47-93638159
| | - Torhild Pedersen
- Department of Biological and Medical Psychology, Faculty of Psychology, University of Bergen, 5020 Bergen, Norway; (T.P.); (J.M.); (J.G.)
| | - Jelena Mrdalj
- Department of Biological and Medical Psychology, Faculty of Psychology, University of Bergen, 5020 Bergen, Norway; (T.P.); (J.M.); (J.G.)
| | - Eirunn Thun
- Department of Clinical Psychology, Faculty of Psychology, University of Bergen, 5020 Bergen, Norway;
| | - Janne Grønli
- Department of Biological and Medical Psychology, Faculty of Psychology, University of Bergen, 5020 Bergen, Norway; (T.P.); (J.M.); (J.G.)
| | - Anette Harris
- Department of Psychosocial Science, Faculty of Psychology, University of Bergen, 5020 Bergen, Norway; (A.H.); (S.P.)
| | - Bjørn Bjorvatn
- Department of Global Public Health and Primary Care, Faculty of Medicine, University of Bergen, 5020 Bergen, Norway; (B.B.); (S.W.)
- Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, 5021 Bergen, Norway
| | - Siri Waage
- Department of Global Public Health and Primary Care, Faculty of Medicine, University of Bergen, 5020 Bergen, Norway; (B.B.); (S.W.)
- Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, 5021 Bergen, Norway
| | - Debra J. Skene
- Chronobiology, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH, UK;
| | - Ståle Pallesen
- Department of Psychosocial Science, Faculty of Psychology, University of Bergen, 5020 Bergen, Norway; (A.H.); (S.P.)
- Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, 5021 Bergen, Norway
- Optentia Research Focus Area, North-West University, Vanderbijlpark 1900, South Africa
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28
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Mouland JW, Martial F, Watson A, Lucas RJ, Brown TM. Cones Support Alignment to an Inconsistent World by Suppressing Mouse Circadian Responses to the Blue Colors Associated with Twilight. Curr Biol 2020; 29:4260-4267.e4. [PMID: 31846668 PMCID: PMC6926481 DOI: 10.1016/j.cub.2019.10.028] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 09/19/2019] [Accepted: 10/16/2019] [Indexed: 01/04/2023]
Abstract
In humans, short-wavelength light evokes larger circadian responses than longer wavelengths [1-3]. This reflects the fact that melanopsin, a key contributor to circadian assessments of light intensity, most efficiently captures photons around 480 nm [4-8] and gives rise to the popular view that "blue" light exerts the strongest effects on the clock. However, in the natural world, there is often no direct correlation between perceived color (as reported by the cone-based visual system) and melanopsin excitation. Accordingly, although the mammalian clock does receive cone-based chromatic signals [9], the influence of color on circadian responses to light remains unclear. Here, we define the nature and functional significance of chromatic influences on the mouse circadian system. Using polychromatic lighting and mice with altered cone spectral sensitivity (Opn1mwR), we generate conditions that differ in color (i.e., ratio of L- to S-cone opsin activation) while providing identical melanopsin and rod activation. When biased toward S-opsin activation (appearing "blue"), these stimuli reliably produce weaker circadian behavioral responses than those favoring L-opsin ("yellow"). This influence of color (which is absent in animals lacking cone phototransduction; Cnga3-/-) aligns with natural changes in spectral composition over twilight, where decreasing solar angle is accompanied by a strong blue shift [9-11]. Accordingly, we find that naturalistic color changes support circadian alignment when environmental conditions render diurnal variations in light intensity weak/ambiguous sources of timing information. Our data thus establish how color contributes to circadian entrainment in mammals and provide important new insight to inform the design of lighting environments that benefit health.
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Affiliation(s)
- Joshua W Mouland
- Centre for Biological Timing, Faculty of Biology, Medicine & Health, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Franck Martial
- Centre for Biological Timing, Faculty of Biology, Medicine & Health, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Alex Watson
- Centre for Biological Timing, Faculty of Biology, Medicine & Health, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Robert J Lucas
- Centre for Biological Timing, Faculty of Biology, Medicine & Health, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Timothy M Brown
- Centre for Biological Timing, Faculty of Biology, Medicine & Health, University of Manchester, Oxford Road, Manchester M13 9PT, UK.
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29
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Predictions of melatonin suppression during the early biological night and their implications for residential light exposures prior to sleeping. Sci Rep 2020; 10:14114. [PMID: 32839489 PMCID: PMC7445277 DOI: 10.1038/s41598-020-70619-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 07/31/2020] [Indexed: 12/20/2022] Open
Abstract
The magnitude of nocturnal melatonin suppression depends upon the spectrum, amount, and duration of light exposure. The functional relationship between melatonin suppression and the light spectrum and amount have been previously described. Only one duration-dependent parameter was needed to extend this functional relationship to predict nocturnal melatonin suppression during the early biological night from a variety of published studies. Those predictions suggest that ambient lighting commonly found in North American homes will not suppress melatonin for durations up to 3 h, whereas extended use of self-luminous displays in the home prior to sleep can.
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Abstract
In this highly digitalized era, sleep disorders are becoming more common and are associated with an increased burden of chronic disease. Shift workers are at an increased risk for both sleep disorders and metabolic syndrome. In this article, the authors outline the connection between circadian discordance, hormonal imbalance, and the development of metabolic syndrome in shift workers. Based on a literature review of animal model studies, observational studies, and clinical trials conducted between August and October of 2018, the authors offer several clinical interventions, including work schedules, light therapy, medications, and dietary habits to improve the circadian synchronicity of shift workers and reduce their risk of morbidity and mortality. It is important for physicians to be familiar with the consequences of shift work and ways to mitigate the risks for this patient population.
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31
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Brown TM. Melanopic illuminance defines the magnitude of human circadian light responses under a wide range of conditions. J Pineal Res 2020; 69:e12655. [PMID: 32248548 DOI: 10.1111/jpi.12655] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 02/28/2020] [Accepted: 03/27/2020] [Indexed: 12/18/2022]
Abstract
Ocular light drives a range of nonvisual responses in humans including suppression of melatonin secretion and circadian phase resetting. These responses are driven by intrinsically photosensitive retinal ganglion cells (ipRGCs) which combine intrinsic, melanopsin-based, phototransduction with extrinsic rod/cone-mediated signals. As a result of this arrangement, it has remained unclear how best to quantify light to predict its nonvisual effects. To address this, we analysed data from nineteen different laboratory studies that measured melatonin suppression, circadian phase resetting and/or alerting responses in humans to a wide array of stimulus types, intensities and durations with or without pupil dilation. Using newly established SI-compliant metrics to quantify ipRGC-influenced responses to light, we show that melanopic illuminance consistently provides the best available predictor for responses of the human circadian system. In almost all cases, melanopic illuminance is able to fully account for differences in sensitivity to stimuli of varying spectral composition, acting to drive responses that track variations in illumination characteristic of those encountered over civil twilight (~1-1000 lux melanopic equivalent daylight illuminance). Collectively, our data demonstrate widespread utility of melanopic illuminance as a metric for predicting the circadian impact of environmental illumination. These data therefore provide strong support for the use of melanopic illuminance as the basis for guidelines that seek to regulate light exposure to benefit human health and to inform future lighting design.
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Affiliation(s)
- Timothy M Brown
- Centre for Biological Timing, Faculty of Medicine, Biology and Health, University of Manchester, Manchester, UK
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32
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Moore-Ede M, Heitmann A, Guttkuhn R. Circadian Potency Spectrum with Extended Exposure to Polychromatic White LED Light under Workplace Conditions. J Biol Rhythms 2020; 35:405-415. [PMID: 32539484 PMCID: PMC7343335 DOI: 10.1177/0748730420923164] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Electric light has enabled humans to conquer the night, but light exposure at night can disrupt the circadian timing system and is associated with a diverse range of health disorders. To provide adequate lighting for visual tasks without disrupting the human circadian timing system, a precise definition of circadian spectral sensitivity is required. Prior attempts to define the circadian spectral sensitivity curve have used short (≤90-min) monochromatic light exposures in dark-adapted human subjects or in vitro dark-adapted isolated retina or melanopsin. Several lines of evidence suggest that these dark-adapted circadian spectral sensitivity curves, in addition to 430- to 499-nm (blue) wavelength sensitivity, may include transient 400- to 429-nm (violet) and 500- to 560-nm (green) components mediated by cone- and rod-originated extrinsic inputs to intrinsically photosensitive retinal ganglion cells (ipRGCs), which decay over the first 2 h of extended light exposure. To test the hypothesis that the human circadian spectral sensitivity in light-adapted conditions may have a narrower, predominantly blue, sensitivity, we used 12-h continuous exposures of light-adapted healthy human subjects to 6 polychromatic white light-emitting diode (LED) light sources with diverse spectral power distributions at recommended workplace levels of illumination (540 lux) to determine their effect on the area under curve of the overnight (2000-0800 h) salivary melatonin. We derived a narrow steady-state human Circadian Potency spectral sensitivity curve with a peak at 477 nm and a full-width half-maximum of 438 to 493 nm. This light-adapted Circadian Potency spectral sensitivity permits the development of spectrally engineered LED light sources to minimize circadian disruption and address the health risks of light exposure at night in our 24/7 society, by alternating between daytime circadian stimulatory white light spectra and nocturnal circadian protective white light spectra.
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Affiliation(s)
- Martin Moore-Ede
- Circadian Light Research Center, Circadian ZircLight, Inc., Stoneham, Massachusetts
| | - Anneke Heitmann
- Circadian Light Research Center, Circadian ZircLight, Inc., Stoneham, Massachusetts
- Data Analytics Department, Circadian Technologies, Inc., Stoneham, Massachusetts
| | - Rainer Guttkuhn
- Data Analytics Department, Circadian Technologies, Inc., Stoneham, Massachusetts
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33
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Duda M, Domagalik A, Orlowska-Feuer P, Krzysztynska-Kuleta O, Beldzik E, Smyk MK, Stachurska A, Oginska H, Jeczmien-Lazur JS, Fafrowicz M, Marek T, Lewandowski MH, Sarna T. Melanopsin: From a small molecule to brain functions. Neurosci Biobehav Rev 2020; 113:190-203. [DOI: 10.1016/j.neubiorev.2020.03.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 03/05/2020] [Accepted: 03/09/2020] [Indexed: 12/29/2022]
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34
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Dominoni DM, Kjellberg Jensen J, de Jong M, Visser ME, Spoelstra K. Artificial light at night, in interaction with spring temperature, modulates timing of reproduction in a passerine bird. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2020; 30:e02062. [PMID: 31863538 PMCID: PMC7187248 DOI: 10.1002/eap.2062] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 09/18/2019] [Accepted: 11/05/2019] [Indexed: 05/09/2023]
Abstract
The ecological impact of artificial light at night (ALAN) on phenological events such as reproductive timing is increasingly recognized. In birds, previous experiments under controlled conditions showed that ALAN strongly advances gonadal growth, but effects on egg-laying date are less clear. In particular, effects of ALAN on timing of egg laying are found to be year-dependent, suggesting an interaction with climatic conditions such as spring temperature, which is known have strong effects on the phenology of avian breeding. Thus, we hypothesized that ALAN and temperature interact to regulate timing of reproduction in wild birds. Field studies have suggested that sources of ALAN rich in short wavelengths can lead to stronger advances in egg-laying date. We therefore tested this hypothesis in the Great Tit (Parus major), using a replicated experimental set-up where eight previously unlit forest transects were illuminated with either white, green, or red LED light, or left dark as controls. We measured timing of egg laying for 619 breeding events spread over six consecutive years and obtained temperature data for all sites and years. We detected overall significantly earlier egg-laying dates in the white and green light vs. the dark treatment, and similar trends for red light. However, there was a strong interannual variability in mean egg-laying dates in all treatments, which was explained by spring temperature. We did not detect any fitness consequence of the changed timing of egg laying due to ALAN, which suggests that advancing reproduction in response to ALAN might be adaptive.
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Affiliation(s)
- Davide M. Dominoni
- Department of Animal EcologyNetherlands Institute of Ecology (NIOO‐KNAW)WageningenThe Netherlands
- Institute of Biodiversity, Animal Health and Comparative MedicineUniversity of GlasgowGlasgowG128PG United Kingdom
| | | | - Maaike de Jong
- Department of Animal EcologyNetherlands Institute of Ecology (NIOO‐KNAW)WageningenThe Netherlands
- Plant Ecology and Nature Conservation GroupWageningen UniversityWageningenThe Netherlands
| | - Marcel E. Visser
- Department of Animal EcologyNetherlands Institute of Ecology (NIOO‐KNAW)WageningenThe Netherlands
| | - Kamiel Spoelstra
- Department of Animal EcologyNetherlands Institute of Ecology (NIOO‐KNAW)WageningenThe Netherlands
- Plant Ecology and Nature Conservation GroupWageningen UniversityWageningenThe Netherlands
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35
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Rzepka-Migut B, Paprocka J. Melatonin-Measurement Methods and the Factors Modifying the Results. A Systematic Review of the Literature. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:E1916. [PMID: 32183489 PMCID: PMC7142625 DOI: 10.3390/ijerph17061916] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Revised: 03/04/2020] [Accepted: 03/06/2020] [Indexed: 01/11/2023]
Abstract
Melatonin plays an important role in regulating the sleep-wake cycle and adaptation to environmental changes. Concentration measurements in bioliquids such as serum/plasma, saliva and urine are widely used to assess peripheral rhythm. The aim of the study was to compare methods and conditions of determinations carried out with the identification of factors potentially affecting the measurements obtained. We have identified a group of modifiable and unmodifiable factors that facilitate data interpretation. Knowledge of modifiers allows you to carefully plan the test protocol and then compare the results. There is no one universal sampling standard, because the choice of method and biofluid depends on the purpose of the study and the research group.
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Affiliation(s)
- Beata Rzepka-Migut
- Department of Pediatric Neurology and Pediatrics, St. Queen Jadwiga’s Regional Clinical Hospital No 2 Rzeszów, 35-301 Rzeszów, Poland;
| | - Justyna Paprocka
- Department of Pediatric Neurology, Faculty of Medical Sciences, Medical University of Silesia, 40-752 Katowice, Poland
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Cajochen C, Reichert C, Maire M, Schlangen LJM, Schmidt C, Viola AU, Gabel V. Evidence That Homeostatic Sleep Regulation Depends on Ambient Lighting Conditions during Wakefulness. Clocks Sleep 2019; 1:517-531. [PMID: 33089184 PMCID: PMC7445844 DOI: 10.3390/clockssleep1040040] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 12/09/2019] [Indexed: 11/16/2022] Open
Abstract
We examined whether ambient lighting conditions during extended wakefulness modulate the homeostatic response to sleep loss as indexed by. slow wave sleep (SWS) and electroencephalographic (EEG) slow-wave activity (SWA) in healthy young and older volunteers. Thirty-eight young and older participants underwent 40 hours of extended wakefulness [i.e., sleep deprivation (SD)] once under dim light (DL: 8 lux, 2800 K), and once under either white light (WL: 250 lux, 2800 K) or blue-enriched white light (BL: 250 lux, 9000 K) exposure. Subjective sleepiness was assessed hourly and polysomnography was quantified during the baseline night prior to the 40-h SD and during the subsequent recovery night. Both the young and older participants responded with a higher homeostatic sleep response to 40-h SD after WL and BL than after DL. This was indexed by a significantly faster intra-night accumulation of SWS and a significantly higher response in relative EEG SWA during the recovery night after WL and BL than after DL for both age groups. No significant differences were observed between the WL and BL condition for these two particular SWS and SWA measures. Subjective sleepiness ratings during the 40-h SD were significantly reduced under both WL and BL compared to DL, but were not significantly associated with markers of sleep homeostasis in both age groups. Our data indicate that not only the duration of prior wakefulness, but also the experienced illuminance during wakefulness affects homeostatic sleep regulation in humans. Thus, working extended hours under low illuminance may negatively impact subsequent sleep intensity in humans.
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Affiliation(s)
- Christian Cajochen
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Wilhelm Kleinstr. 27, CH-4002 Basel, Switzerland;
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Birmannsgasse 8, CHF-4055 Basel, Switzerland
| | - Carolin Reichert
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Wilhelm Kleinstr. 27, CH-4002 Basel, Switzerland;
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Birmannsgasse 8, CHF-4055 Basel, Switzerland
| | - Micheline Maire
- Institute of Primary Health Care (BIHAM), University of Bern, 3012 Bern, Switzerland;
| | - Luc J M Schlangen
- Intelligent Lighting Institute, School of Innovation Sciences, Department of Human Technology Interaction, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands;
| | - Christina Schmidt
- GIGA-Research, Cyclotron Research Centre-In Vivo Imaging Unit, Psychology and Neuroscience of Cognition Research Unit (PsyNCog), Faculty of Psychology and Educational Sciences, University of Liège, 4000 Liège, Belgium;
| | | | - Virginie Gabel
- Department of Psychiatry and Behavioral Sciences, Stanford University, Palo Alto, CA 94305, USA;
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Abstract
Artificial light at night (ALAN) is increasing exponentially worldwide, accelerated by the transition to new efficient lighting technologies. However, ALAN and resulting light pollution can cause unintended physiological consequences. In vertebrates, production of melatonin—the “hormone of darkness” and a key player in circadian regulation—can be suppressed by ALAN. In this paper, we provide an overview of research on melatonin and ALAN in vertebrates. We discuss how ALAN disrupts natural photic environments, its effect on melatonin and circadian rhythms, and different photoreceptor systems across vertebrate taxa. We then present the results of a systematic review in which we identified studies on melatonin under typical light-polluted conditions in fishes, amphibians, reptiles, birds, and mammals, including humans. Melatonin is suppressed by extremely low light intensities in many vertebrates, ranging from 0.01–0.03 lx for fishes and rodents to 6 lx for sensitive humans. Even lower, wavelength-dependent intensities are implied by some studies and require rigorous testing in ecological contexts. In many studies, melatonin suppression occurs at the minimum light levels tested, and, in better-studied groups, melatonin suppression is reported to occur at lower light levels. We identify major research gaps and conclude that, for most groups, crucial information is lacking. No studies were identified for amphibians and reptiles and long-term impacts of low-level ALAN exposure are unknown. Given the high sensitivity of vertebrate melatonin production to ALAN and the paucity of available information, it is crucial to research impacts of ALAN further in order to inform effective mitigation strategies for human health and the wellbeing and fitness of vertebrates in natural ecosystems.
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Gladanac B, Jonkman J, Shapiro CM, Brown TJ, Ralph MR, Casper RF, Rahman SA. Removing Short Wavelengths From Polychromatic White Light Attenuates Circadian Phase Resetting in Rats. Front Neurosci 2019; 13:954. [PMID: 31551702 PMCID: PMC6746919 DOI: 10.3389/fnins.2019.00954] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 08/23/2019] [Indexed: 11/13/2022] Open
Abstract
Visible light is the principal stimulus for resetting the mammalian central circadian pacemaker. Circadian phase resetting is most sensitive to short-wavelength (blue) visible light. We examined the effects of removing short-wavelengths < 500 nm from polychromatic white light using optical filters on circadian phase resetting in rats. Under high irradiance conditions, both long- (7 h) and short- (1 h) duration short-wavelength filtered (< 500 nm) light exposure attenuated phase-delay shifts in locomotor activity rhythms by (∼40-50%) as compared to unfiltered light exposure. However, there was no attenuation in phase resetting under low irradiance conditions. Additionally, the reduction in phase-delay shifts corresponded to regionally specific attenuation in molecular markers of pacemaker activation in response to light exposure, including c-FOS, Per1 and Per2. These results demonstrate that removing short-wavelengths from polychromatic white light can attenuate circadian phase resetting in an irradiance dependent manner. These results have important implications for designing and optimizing lighting interventions to enhance circadian adaptation.
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Affiliation(s)
- Bojana Gladanac
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
| | - James Jonkman
- Advanced Optical Microscopy Facility, University Health Network, Toronto, ON, Canada
| | - Colin M Shapiro
- Department of Psychiatry and Ophthalmology, University of Toronto, Toronto, ON, Canada.,Youthdale Child and Adolescent Sleep Centre, Toronto, ON, Canada
| | - Theodore J Brown
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.,Division of Reproductive Endocrinology and Infertility, University of Toronto, Toronto, ON, Canada
| | - Martin R Ralph
- Department of Psychology, University of Toronto, Toronto, ON, Canada
| | - Robert F Casper
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.,Division of Reproductive Endocrinology and Infertility, University of Toronto, Toronto, ON, Canada
| | - Shadab A Rahman
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston, MA, United States.,Division of Sleep Medicine, Harvard Medical School, Boston, MA, United States
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39
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Abstract
Humans live in a 24-hour environment, in which light and darkness follow a diurnal pattern. Our circadian pacemaker, the suprachiasmatic nuclei (SCN) in the hypothalamus, is entrained to the 24-hour solar day via a pathway from the retina and synchronises our internal biological rhythms. Rhythmic variations in ambient illumination impact behaviours such as rest during sleep and activity during wakefulness as well as their underlying biological processes. Rather recently, the availability of artificial light has substantially changed the light environment, especially during evening and night hours. This may increase the risk of developing circadian rhythm sleep-wake disorders (CRSWD), which are often caused by a misalignment of endogenous circadian rhythms and external light-dark cycles. While the exact relationship between the availability of artificial light and CRSWD remains to be established, nocturnal light has been shown to alter circadian rhythms and sleep in humans. On the other hand, light can also be used as an effective and noninvasive therapeutic option with little to no side effects, to improve sleep,mood and general well-being. This article reviews our current state of knowledge regarding the effects of light on circadian rhythms, sleep, and mood.
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Affiliation(s)
- Christine Blume
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel (UPK), Basel, Switzerland.,Transfaculty Research Platform Molecular and Cognitive Neurosciences (MCN), University of Basel, Basel, Switzerland.,Centre for Cognitive Neuroscience, University of Salzburg, Salzburg, Austria
| | - Corrado Garbazza
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel (UPK), Basel, Switzerland.,Transfaculty Research Platform Molecular and Cognitive Neurosciences (MCN), University of Basel, Basel, Switzerland
| | - Manuel Spitschan
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel (UPK), Basel, Switzerland.,Transfaculty Research Platform Molecular and Cognitive Neurosciences (MCN), University of Basel, Basel, Switzerland.,Department of Experimental Psychology, University of Oxford, Oxford, UK
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Abstract
Melanopsin is a short-wavelength-sensitive photopigment that was discovered only around 20 years ago. It is expressed in the cell bodies and processes of a subset of retinal ganglion cells in the retina (the intrinsically photosensitive retinal ganglion cells; ipRGCs), thereby allowing them to signal light even in the absence of cone and rod input. Many of the fundamental properties of melanopsin signalling in humans for both visual (e.g. detection, discrimination, brightness estimation) and non-visual function (e.g. melatonin suppression, circadian phase shifting) remain to be elucidated. Here, we give an overview of what we know about melanopsin contributions in visual function and non-visual function.
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Affiliation(s)
- Manuel Spitschan
- Department of Experimental Psychology, University of Oxford, United Kingdom.,Centre for Chronobiology, Psychiatric Hospital of the University of Basel (UPK), Switzerland.,Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Switzerland
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Nagare R, Rea MS, Plitnick B, Figueiro MG. Effect of White Light Devoid of "Cyan" Spectrum Radiation on Nighttime Melatonin Suppression Over a 1-h Exposure Duration. J Biol Rhythms 2019; 34:195-204. [PMID: 30821188 DOI: 10.1177/0748730419830013] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The intrinsically photosensitive retinal ganglion cells are the main conduit of the light signal emanating from the retina to the biological clock located in the suprachiasmatic nuclei of the hypothalamus. Lighting manufacturers are developing white light sources that are devoid of wavelengths around 480 nm ("cyan gap") to reduce their impact on the circadian system. The present study was designed to investigate whether exposure to a "cyan-gap," 3000 K white light source, spectrally tuned to reduce radiant power between 475 and 495 nm (reducing stimulation of the melanopsin-containing photoreceptor), would suppress melatonin less than a conventional 3000 K light source. The study's 2 phases employed a within-subjects experimental design involving the same 16 adult participants. In Phase 1, participants were exposed for 1 h to 3 experimental conditions over the course of 3 consecutive weeks: 1) dim light control (<5 lux at the eyes); 2) 800 lux at the eyes of a 3000 K light source; and 3) 800 lux at the eyes of a 3000 K, "cyan-gap" modified (3000 K mod) light source. The same protocol was repeated in Phase 2, but light levels were reduced to 400 lux at the eyes. As hypothesized, there were significant main effects of light level ( F1,12 = 9.1, p < 0.05, ηp² = 0.43) and exposure duration ( F1,12 = 47.7, p < 0.05, ηp² = 0.80) but there was no significant main effect of spectrum ( F1,12 = 0.16, p > 0.05, ηp² = 0.01). There were no significant interactions with spectrum. Contrary to our model predictions, our results showed that short-term exposures (≤ 1 h) to "cyan-gap" light sources suppressed melatonin similarly to conventional light sources of the same CCT and photopic illuminance at the eyes.
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Affiliation(s)
- Rohan Nagare
- Lighting Research Center, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Mark S Rea
- Lighting Research Center, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Barbara Plitnick
- Lighting Research Center, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Mariana G Figueiro
- Lighting Research Center, Rensselaer Polytechnic Institute, Troy, NY, USA
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