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Zohdi H, Märki J, Scholkmann F, Wolf U. Cerebral, systemic physiological and behavioral responses to colored light exposure during a cognitive task: A SPA-fNIRS study. Behav Brain Res 2024; 462:114884. [PMID: 38296201 DOI: 10.1016/j.bbr.2024.114884] [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] [Received: 08/28/2023] [Revised: 01/25/2024] [Accepted: 01/26/2024] [Indexed: 02/10/2024]
Abstract
Colored light has important implications for human health and well-being, as well as for the aesthetics and function of various environments. In addition to its effects on visual function, colored light has significant effects on cognitive performance, behavior and systemic physiology. The aim of the current study was to comprehensively investigate how colored light exposure (CLE) combined with a cognitive task (2-back) affects performance, cerebral hemodynamics, oxygenation, and systemic physiology as assessed by systemic physiology augmented functional near-infrared spectroscopy (SPA-fNIRS). 36 healthy subjects (22 female, 14 male, age 26.3 ± 5.7 years) were measured twice on two different days. They were exposed to the sequence of blue and red light or vice versa in a randomized crossover design. During the CLE, the subjects were asked to perform a 2-back task. The 2-back task performance was correlated with changes in the concentration of oxygenated hemoglobin in the prefrontal cortex (red: r = -0.37, p = 0.001; blue: r = -0.33, p = 0.004) and the high-frequency component of the heart rate variability (red: r = 0.35, p = 0.003; blue: r = 0.25, p = 0.04). These changes were independent of the CLE. Sequence-dependent effects were observed for fNIRS signals at the visual cortex (VC) and for electrodermal activity (EDA). While both colors caused relatively similar changes in the VC and EDA at the position of the first exposure, blue and red light caused greater changes in the VC and EDA, respectively, in the second exposure. There was no significant difference in the subjects' 2-back task performance between the CLE (p = 0.46). The results of this study provide new insights into how human physiology and behavior respond to colored light exposure. Our findings are important for understanding the impact of colored light in our daily lives and its potential applications in a variety of settings, including education, the workplace and healthcare.
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Affiliation(s)
- Hamoon Zohdi
- Institute of Complementary and Integrative Medicine, University of Bern, 3012 Bern, Switzerland; Biomedical Optics Research Laboratory, Department of Neonatology, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland.
| | - Josefa Märki
- Institute of Complementary and Integrative Medicine, University of Bern, 3012 Bern, Switzerland
| | - Felix Scholkmann
- Institute of Complementary and Integrative Medicine, University of Bern, 3012 Bern, Switzerland; Biomedical Optics Research Laboratory, Department of Neonatology, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland
| | - Ursula Wolf
- Institute of Complementary and Integrative Medicine, University of Bern, 3012 Bern, Switzerland
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2
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Mahoney HL, Schmidt TM. The cognitive impact of light: illuminating ipRGC circuit mechanisms. Nat Rev Neurosci 2024; 25:159-175. [PMID: 38279030 DOI: 10.1038/s41583-023-00788-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/19/2023] [Indexed: 01/28/2024]
Abstract
Ever-present in our environments, light entrains circadian rhythms over long timescales, influencing daily activity patterns, health and performance. Increasing evidence indicates that light also acts independently of the circadian system to directly impact physiology and behaviour, including cognition. Exposure to light stimulates brain areas involved in cognition and appears to improve a broad range of cognitive functions. However, the extent of these effects and their mechanisms are unknown. Intrinsically photosensitive retinal ganglion cells (ipRGCs) have emerged as the primary conduit through which light impacts non-image-forming behaviours and are a prime candidate for mediating the direct effects of light on cognition. Here, we review the current state of understanding of these effects in humans and mice, and the tools available to uncover circuit-level and photoreceptor-specific mechanisms. We also address current barriers to progress in this area. Current and future efforts to unravel the circuits through which light influences cognitive functions may inform the tailoring of lighting landscapes to optimize health and cognitive function.
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Affiliation(s)
- Heather L Mahoney
- Department of Neurobiology, Northwestern University, Evanston, IL, USA.
| | - Tiffany M Schmidt
- Department of Neurobiology, Northwestern University, Evanston, IL, USA.
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3
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Didikoglu A, Mohammadian N, Johnson S, van Tongeren M, Wright P, Casson AJ, Brown TM, Lucas RJ. Associations between light exposure and sleep timing and sleepiness while awake in a sample of UK adults in everyday life. Proc Natl Acad Sci U S A 2023; 120:e2301608120. [PMID: 37812713 PMCID: PMC10589638 DOI: 10.1073/pnas.2301608120] [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: 01/29/2023] [Accepted: 08/11/2023] [Indexed: 10/11/2023] Open
Abstract
Experimental and interventional studies show that light can regulate sleep timing and sleepiness while awake by setting the phase of circadian rhythms and supporting alertness. The extent to which differences in light exposure explain variations in sleep and sleepiness within and between individuals in everyday life remains less clear. Here, we establish a method to address this deficit, incorporating an open-source wearable wrist-worn light logger (SpectraWear) and smartphone-based online data collection. We use it to simultaneously record longitudinal light exposure (in melanopic equivalent daylight illuminance), sleep timing, and subjective alertness over seven days in a convenience sample of 59 UK adults without externally imposed circadian challenge (e.g., shift work or jetlag). Participants reliably had strong daily rhythms in light exposure but frequently were exposed to less light during the daytime and more light in pre-bedtime and sleep episodes than recommended [T. M. Brown et al., PLoS Biol. 20, e3001571 (2022)]. Prior light exposure over several hours was associated with lower subjective sleepiness with, in particular, brighter light in the late sleep episode and after wake linked to reduced early morning sleepiness (sleep inertia). Higher pre-bedtime light exposure was associated with longer sleep onset latency. Early sleep timing was correlated with more reproducible and robust daily patterns of light exposure and higher daytime/lower night-time light exposure. Our study establishes a method for collecting longitudinal sleep and health/performance data in everyday life and provides evidence of associations between light exposure and important determinants of sleep health and performance.
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Affiliation(s)
- Altug Didikoglu
- Centre for Biological Timing, Division of Neuroscience, School of Biological Sciences, Faculty of Biology Medicine and Health, University of Manchester, ManchesterM13 9PL, United Kingdom
- Department of Neuroscience, Izmir Institute of Technology, Gulbahce, Izmir35430, Turkey
| | - Navid Mohammadian
- Department of Electrical & Electronic Engineering, School of Engineering, Faculty of Science and Engineering, University of Manchester, ManchesterM13 9PL, United Kingdom
| | - Sheena Johnson
- Thomas Ashton Institute, People, Management and Organisation Division, Alliance Manchester Business School, Faculty of Humanities, University of Manchester, ManchesterM13 9PL, United Kingdom
| | - Martie van Tongeren
- Thomas Ashton Institute, Centre for Occupational and Environmental Health, Division of Population Health, Health Services Research & Primary Care, School of Health Sciences, Faculty of Biology Medicine and Health, University of Manchester, ManchesterM13 9PL, United Kingdom
| | - Paul Wright
- Department of Electrical & Electronic Engineering, School of Engineering, Faculty of Science and Engineering, University of Manchester, ManchesterM13 9PL, United Kingdom
| | - Alexander J. Casson
- Department of Electrical & Electronic Engineering, School of Engineering, Faculty of Science and Engineering, University of Manchester, ManchesterM13 9PL, United Kingdom
| | - Timothy M. Brown
- Centre for Biological Timing, Division of Diabetes Endocrinology and Gastroenterology, School of Medical Sciences, Faculty of Biology Medicine and Health, University of Manchester, ManchesterM13 9PL, United Kingdom
| | - Robert J. Lucas
- Centre for Biological Timing, Division of Neuroscience, School of Biological Sciences, Faculty of Biology Medicine and Health, University of Manchester, ManchesterM13 9PL, United Kingdom
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4
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Brighter Time: A Smartphone App Recording Cognitive Task Performance and Illuminance in Everyday Life. Clocks Sleep 2022; 4:577-594. [PMID: 36278538 PMCID: PMC9589962 DOI: 10.3390/clockssleep4040045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 09/20/2022] [Accepted: 10/17/2022] [Indexed: 11/07/2022] Open
Abstract
Light is an influential regulator of behavioural and physiological state in mammals. Features of cognitive performance such as memory, vigilance and alertness can be altered by bright light exposure under laboratory and field conditions. However, the importance of light as a regulator of performance in everyday life is hard to assess and has so far remained largely unclear. We set out to address this uncertainty by developing a tool to capture measures of cognitive performance and light exposure, at scale, and during everyday life. To this end, we generated an app (Brighter Time) which incorporated a psychomotor vigilance (PVT), an N-back and a visual search task with questionnaire-based assessments of demographic characteristics, general health, chronotype and sleep. The app also measured illuminance during task completion using the smartphone's intrinsic light meter. We undertook a pilot feasibility study of Brighter Time based on 91-week-long acquisition phases within a convenience sample (recruited by local advertisements and word of mouth) running Brighter Time on their own smartphones over two study phases in winter and summer. Study compliance was suitable (median = 20/21 requested task completions per subject). Statistically significant associations were observed between subjective sleepiness and performance in all tasks. Significant daily variations in PVT and visual search performance were also observed. Higher illuminance was associated with reduced reaction time and lower inverse efficiency score in the visual search. Brighter Time thus represents a viable option for large-scale collection of cognitive task data in everyday life, and is able to reveal associations between task performance and sleepiness, time of day and current illuminance. Brighter Time's utility could be extended to exploring associations with longer-term patterns of light exposure and/or other light metrics by integrating with wearable light meters.
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5
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Danilenko KV. Objective Measures of Immediate “Energizing” Effect of Light: Studies Review and Data Analysis. Clocks Sleep 2022; 4:475-496. [PMID: 36278531 PMCID: PMC9589941 DOI: 10.3390/clockssleep4040038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 09/18/2022] [Accepted: 09/20/2022] [Indexed: 11/16/2022] Open
Abstract
While the energizing effect of light has been known since the early years of light therapy, its reliable detection using objective measures is still not well-established. This review aims to ascertain the immediate energizing effect of light and determine its best indicators. Sixty-four articles published before July 2022 were included in the review. The articles described 72 (sub-)studies performed in healthy individuals. Fourteen measures were analyzed. The analysis showed that light causes an energizing effect that can be best documented by measuring core (rectal) body temperature: the proportion of the studies revealing increasing, unchanging, and decreasing rectal temperature was 13/6/1. The second most suitable indicator was heart rate (10/22/1), which showed concordant changes with rectal temperature (a trend, seven mutual studies). There is no evidence from the reviewed articles that oxygen consumption, skin conductance, blood pressure, heart rate variability, non-rectal inner temperature (combined digestive, tympanic, and oral), skin temperature, or cortisol levels can provide light effect detection. Four other measures were found to be unsuitable as well but with less certainty due to the low number of studies (≤3): skin blood flow, noradrenaline, salivary alpha-amylase, and thyroid-stimulating hormone levels. On the other hand, light exposure had a noticeable effect on sympathetic nerve activity measured using microneurography; however, this measure can be accepted as a marker only tentatively as it was employed in a single study. The analysis took into account three factors—study limitation in design/analysis, use of light in day- or nighttime, and relative brightness of the light stimulus—that were found to significantly influence some of the analyzed variables. The review indicates that the energizing effect of light in humans can be reliably detected using rectal temperature and heart rate.
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Lok R, Woelders T, van Koningsveld MJ, Oberman K, Fuhler SG, Beersma DGM, Hut RA. Bright Light Increases Alertness and Not Cortisol in Healthy Men: A Forced Desynchrony Study Under Dim and Bright Light (I). J Biol Rhythms 2022; 37:403-416. [PMID: 35686534 PMCID: PMC9326799 DOI: 10.1177/07487304221096945] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Light-induced improvements in alertness are more prominent during nighttime than during the day, suggesting that alerting effects of light may depend on internal clock time or wake duration. Relative contributions of both factors can be quantified using a forced desynchrony (FD) designs. FD designs have only been conducted under dim light conditions (<10 lux) since light above this amount can induce non-uniform phase progression of the circadian pacemaker (also called relative coordination). This complicates the mathematical separation of circadian clock phase from homeostatic sleep pressure effects. Here we investigate alerting effects of light in a novel 4 × 18 h FD protocol (5 h sleep, 13 h wake) under dim (6 lux) and bright light (1300 lux) conditions. Hourly saliva samples (melatonin and cortisol assessment) and 2-hourly test sessions were used to assess effects of bright light on subjective and objective alertness (electroencephalography and performance). Results reveal (1) stable free-running cortisol rhythms with uniform phase progression under both light conditions, suggesting that FD designs can be conducted under bright light conditions (1300 lux), (2) subjective alerting effects of light depend on elapsed time awake but not circadian clock phase, while (3) light consistently improves objective alertness independent of time awake or circadian clock phase. Reconstructing the daily time course by combining circadian clock phase and wake duration effects indicates that performance is improved during daytime, while subjective alertness remains unchanged. This suggests that high-intensity indoor lighting during the regular day might be beneficial for mental performance, even though this may not be perceived as such.
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Affiliation(s)
- R Lok
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands.,Current address: Department of Psychiatry and Behavioral Sciences, Stanford University, Palo Alto, California, USA.,University of Groningen, Leeuwarden, the Netherlands
| | - T Woelders
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | - M J van Koningsveld
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | - K Oberman
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | - S G Fuhler
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | - D G M Beersma
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | - R A Hut
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
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7
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Lok R, Joyce DS, Zeitzer JM. Impact of daytime spectral tuning on cognitive function. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2022; 230:112439. [PMID: 35398657 DOI: 10.1016/j.jphotobiol.2022.112439] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 03/22/2022] [Accepted: 03/25/2022] [Indexed: 06/14/2023]
Abstract
Light at night can improve alertness and cognition. Exposure to daytime light, however, has yielded less conclusive results. In addition to direct effects, daytime light may also mitigate the impact of nocturnal light exposure on alertness. To examine the impact of daytime lighting on daytime cognitive performance, and evening alertness, we studied nine healthy individuals using a within subject crossover design. On four visits, participants were exposed to one of four lighting conditions for 10 h (dim fluorescent, room fluorescent, broad-spectrum LED, standard white LED; the latter three conditions were matched for 100 lx) followed by an exposure to bright evening light. Cognitive performance, subjective and objective measures of alertness were regularly obtained. While daytime alertness was not impacted by light exposure, the broad-spectrum LED light improved several aspects of daytime cognition. The impact of evening light on alertness was not mitigated by the pre-exposure to different daytime lighting conditions. Results suggest that daytime exposure to white light with high melanopic efficacy has the potential to improve daytime cognitive function and that such improvements are likely to be direct rather than a consequence of light-induced changes in alertness.
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Affiliation(s)
- Renske Lok
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305, United States of America
| | - Daniel S Joyce
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305, United States of America; Department of Psychology, University of Nevada, Reno, Reno, NV 89557, United States of America
| | - Jamie M Zeitzer
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305, United States of America; Mental Illness Research Education and Clinical Center, VA Palo Alto Health Care System, Palo Alto, CA 94304, United States of America.
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8
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Siraji MA, Kalavally V, Schaefer A, Haque S. Effects of Daytime Electric Light Exposure on Human Alertness and Higher Cognitive Functions: A Systematic Review. Front Psychol 2022; 12:765750. [PMID: 35069337 PMCID: PMC8766646 DOI: 10.3389/fpsyg.2021.765750] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 11/30/2021] [Indexed: 11/13/2022] Open
Abstract
This paper reports the results of a systematic review conducted on articles examining the effects of daytime electric light exposure on alertness and higher cognitive functions. For this, we selected 59 quantitative research articles from 11 online databases. The review protocol was registered with PROSPERO (CRD42020157603). The results showed that both short-wavelength dominant light exposure and higher intensity white light exposure induced alertness. However, those influences depended on factors like the participants' homeostatic sleep drive and the time of day the participants received the light exposure. The relationship between light exposure and higher cognitive functions was not as straightforward as the alerting effect. The optimal light property for higher cognitive functions was reported dependent on other factors, such as task complexity and properties of control light. Among the studies with short-wavelength dominant light exposure, ten studies (morning: 3; afternoon: 7) reported beneficial effects on simple task performances (reaction time), and four studies (morning: 3; afternoon: 1) on complex task performances. Four studies with higher intensity white light exposure (morning: 3; afternoon: 1) reported beneficial effects on simple task performance and nine studies (morning: 5; afternoon: 4) on complex task performance. Short-wavelength dominant light exposure with higher light intensity induced a beneficial effect on alertness and simple task performances. However, those effects did not hold for complex task performances. The results indicate the need for further studies to understand the influence of short-wavelength dominant light exposure with higher illuminance on alertness and higher cognitive functions.
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Affiliation(s)
- Mushfiqul Anwar Siraji
- Department of Psychology, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Subang Jaya, Malaysia
| | - Vineetha Kalavally
- Department of Electrical and Computer Systems Engineering, School of Engineering, Monash University Malaysia, Subang Jaya, Malaysia
| | - Alexandre Schaefer
- Department of Psychology, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Subang Jaya, Malaysia.,School of Medical and Life Sciences, Sunway University, Subang Jaya, Malaysia
| | - Shamsul Haque
- Department of Psychology, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Subang Jaya, Malaysia
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9
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Luo X, Ru T, Chen Q, Hsiao FC, Hung CS, Yang CM, Zhou G. Temporal Dynamics of Subjective and Objective Alertness During Exposure to Bright Light in the Afternoon for 5 h. Front Physiol 2021; 12:771605. [PMID: 34950050 PMCID: PMC8691749 DOI: 10.3389/fphys.2021.771605] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 11/08/2021] [Indexed: 11/22/2022] Open
Abstract
Light can induce an alertness response in humans. The effects of exposure to bright light vs. dim light on the levels of alertness during the day, especially in the afternoon, as reported in the literature, are inconsistent. This study employed a multiple measurement strategy to explore the temporal variations in the effects of exposure to bright light vs. regular office light (1,200 lx vs. 200 lx at eye level, 6,500 K) on the alertness of participants for 5 h in the afternoon. In this study, 20 healthy adults (11 female; mean age 23.25 ± 2.3 years) underwent the Karolinska sleepiness scale (KSS), the auditory psychomotor vigilance test (PVT), and the waking electroencephalogram (EEG) test for two levels of light intervention. The results yielded a relatively lower relative delta power and a relatively higher beta power for the 1,200 lx condition in comparison with the 200 lx condition. However, the light conditions elicited no statistically significant differences in the KSS scores and performance with respect to the PVT. The results suggested that exposure to bright light for 5 h in the afternoon could enhance physiological arousal while exerting insignificant effects on subjective feelings and performance abilities relating to the alertness of the participants.
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Affiliation(s)
- Xue Luo
- School of Psychology, South China Normal University, Guangzhou, China
| | - Taotao Ru
- Lab of Light and Physiopsychological Health, National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Optical Information Materials and Technology and Institute of Electronic Paper Displays, South China Normal University, South China Academy of Advanced Optoelectronics, Guangzhou, China
| | - Qingwei Chen
- Lab of Light and Physiopsychological Health, National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Optical Information Materials and Technology and Institute of Electronic Paper Displays, South China Normal University, South China Academy of Advanced Optoelectronics, Guangzhou, China
| | - Fan-Chi Hsiao
- Department of Counseling and Industrial/Organizational Psychology, Ming Chuan University, Taoyuan, Taiwan
| | - Ching-Sui Hung
- Department of Psychology, National Chengchi University, Taipei, Taiwan
| | - Chien-Ming Yang
- Department of Psychology, National Chengchi University, Taipei, Taiwan.,The Research Center for Mind, Brain, and Learning, National Chengchi University, Taipei, Taiwan
| | - Guofu Zhou
- Lab of Light and Physiopsychological Health, National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Optical Information Materials and Technology and Institute of Electronic Paper Displays, South China Normal University, South China Academy of Advanced Optoelectronics, Guangzhou, China
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10
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Zhou Y, Chen Q, Luo X, Li L, Ru T, Zhou G. Does Bright Light Counteract the Post-lunch Dip in Subjective States and Cognitive Performance Among Undergraduate Students? Front Public Health 2021; 9:652849. [PMID: 34164367 PMCID: PMC8215386 DOI: 10.3389/fpubh.2021.652849] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 04/19/2021] [Indexed: 11/24/2022] Open
Abstract
The post-lunch dip in alertness and performance was widely experienced during the early afternoon. Taking a short nap was documented as a practical strategy for habitual nappers to counteract the decline of alertness and performance. Yet, it remains unknown whether bright light exposure in the early afternoon working hours could alleviate the performance deficits caused by a post-lunch nap loss for habitual nappers. Seventeen undergraduate students who had a long-term habit of taking a post-lunch nap were assigned to three interventions: (1) a short nap + normal indoor light (100 lx, 4,000 K at eye level); (2) no nap + normal indoor light, and (3) no nap + blue-enriched bright light (1,000 lx, 6,500 K at eye level), in which subjective alertness (Karolinska Sleepiness Scale, KSS), mood (Positive and Negative Affect Schedule, PANAS), and task performance in sustained attention (psychomotor vigilance test, PVT), response inhibition (go/no-go task), and working memory (paced visual serial addition test, PVSAT) were measured. Results showed that a post-lunch nap deprivation significantly increased subjective sleepiness and negative mood and impaired performance in PVT and PVSAT, while exposure to bright blue-enriched white light vs. normal indoor light in the early afternoon significantly relieved such negative effects on mood, sleepiness, and performance in PVSAT; subjective positive mood and performance in PVT and go/no-go task remained unaffected with light intervention. These findings suggested that bright blue-enriched white light exposure could be a potential strategy for those who are suffering from drowsiness and low working memory following a habitual midday nap loss.
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Affiliation(s)
- Ying Zhou
- Lab of Lighting and Physio-Psychological Health, National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, China
| | - Qingwei Chen
- Lab of Lighting and Physio-Psychological Health, National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, China
| | - Xue Luo
- School of Psychology, South China Normal University, Guangzhou, China
| | - Le Li
- Lab of Lighting and Physio-Psychological Health, National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, China
| | - Taotao Ru
- Lab of Lighting and Physio-Psychological Health, National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, China
| | - Guofu Zhou
- Lab of Lighting and Physio-Psychological Health, National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, China
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11
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Stefani O, Freyburger M, Veitz S, Basishvili T, Meyer M, Weibel J, Kobayashi K, Shirakawa Y, Cajochen C. Changing color and intensity of LED lighting across the day impacts on circadian melatonin rhythms and sleep in healthy men. J Pineal Res 2021; 70:e12714. [PMID: 33378563 DOI: 10.1111/jpi.12714] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 12/22/2020] [Accepted: 12/24/2020] [Indexed: 01/09/2023]
Abstract
We examined whether dynamically changing light across a scheduled 16-h waking day influences sleepiness, cognitive performance, visual comfort, melatonin secretion, and sleep under controlled laboratory conditions in healthy men. Fourteen participants underwent a 49-h laboratory protocol in a repeated-measures study design. They spent the first 5 hours in the evening under standard lighting, followed by an 8-h nocturnal sleep episode at habitual bedtimes. Thereafter, volunteers either woke up to static light or to a dynamic light that changed spectrum and intensity across the scheduled 16-h waking day. Following an 8-h nocturnal sleep episode, the volunteers spent another 11 hours either under static or dynamic light. Static light attenuated the evening rise in melatonin levels more compared to dynamic light as indexed by a significant reduction in the melatonin AUC prior to bedtime during static light only. Participants felt less vigilant in the evening during dynamic light. After dynamic light, sleep latency was significantly shorter in both the baseline and treatment night while sleep structure, sleep quality, cognitive performance, and visual comfort did not significantly differ. The study shows that dynamic changes in spectrum and intensity of light promote melatonin secretion and sleep initiation in healthy men.
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Affiliation(s)
- Oliver Stefani
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland
- Transfaculty Research Platform Molecular and Cognitive Neurosciences (MCN), University of Basel, Basel, Switzerland
| | - Marlène Freyburger
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland
| | - Simon Veitz
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland
| | - Tamara Basishvili
- School of Natural Sciences and Medicine, Tengiz Oniani Laboratory of Sleep-Wakefulness Cycle Study, Ilia State University, Tbilisi, Georgia
| | - Martin Meyer
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland
- Transfaculty Research Platform Molecular and Cognitive Neurosciences (MCN), University of Basel, Basel, Switzerland
| | - Janine Weibel
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland
- Transfaculty Research Platform Molecular and Cognitive Neurosciences (MCN), University of Basel, Basel, Switzerland
| | - Kumpei Kobayashi
- Development and Engineering Department, Toshiba Materials Co. Ltd, Yokohama-City, Japan
| | - Yasuhiro Shirakawa
- Development and Engineering Department, Toshiba Materials Co. Ltd, Yokohama-City, Japan
| | - Christian Cajochen
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland
- Transfaculty Research Platform Molecular and Cognitive Neurosciences (MCN), University of Basel, Basel, Switzerland
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12
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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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13
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Tekieh T, Lockley SW, Robinson PA, McCloskey S, Zobaer MS, Postnova S. Modeling melanopsin-mediated effects of light on circadian phase, melatonin suppression, and subjective sleepiness. J Pineal Res 2020; 69:e12681. [PMID: 32640090 DOI: 10.1111/jpi.12681] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 06/05/2020] [Accepted: 07/01/2020] [Indexed: 12/14/2022]
Abstract
A physiologically based model of arousal dynamics is improved to incorporate the effects of the light spectrum on circadian phase resetting, melatonin suppression, and subjective sleepiness. To account for these nonvisual effects of light, melanopic irradiance replaces photopic illuminance that was used previously in the model. The dynamic circadian oscillator is revised according to the melanopic irradiance definition and tested against experimental circadian phase resetting dose-response and phase response data. Melatonin suppression function is recalibrated against melatonin dose-response data for monochromatic and polychromatic light sources. A new light-dependent term is introduced into the homeostatic weight component of subjective sleepiness to represent the direct alerting effect of light; the new term responds to light change in a time-dependent manner and is calibrated against experimental data. The model predictions are compared to a total of 14 experimental studies containing 26 data sets for 14 different spectral light profiles. The revised melanopic model shows on average 1.4 times lower prediction error for circadian phase resetting compared to the photopic-based model, 3.2 times lower error for melatonin suppression, and 2.1 times lower error for subjective sleepiness. Overall, incorporating melanopic irradiance allowed simulation of wavelength-dependent responses to light and could explain the majority of the observations. Moving forward, models of circadian phase resetting and the direct effects of light on alertness and sleep need to use nonvisual photoreception-based measures of light, for example, melanopic irradiance, instead of the traditionally used illuminance based on the visual system.
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Affiliation(s)
- Tahereh Tekieh
- School of Physics, University of Sydney, Sydney, NSW, Australia
- Cooperative Research Centre for Alertness, Safety and Productivity, Melbourne, Vic., Australia
- Centre of Excellence for Integrative Brain Function, University of Sydney, Sydney, NSW, Australia
| | - Steven W Lockley
- Cooperative Research Centre for Alertness, Safety and Productivity, Melbourne, Vic., Australia
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Melbourne, Vic., Australia
| | - Peter A Robinson
- School of Physics, University of Sydney, Sydney, NSW, Australia
- Cooperative Research Centre for Alertness, Safety and Productivity, Melbourne, Vic., Australia
- Centre of Excellence for Integrative Brain Function, University of Sydney, Sydney, NSW, Australia
- Centre for Translational Sleep and Circadian Neurobiology, University of Sydney, Sydney, NSW, Australia
| | - Stephen McCloskey
- School of Physics, University of Sydney, Sydney, NSW, Australia
- Cooperative Research Centre for Alertness, Safety and Productivity, Melbourne, Vic., Australia
| | - M S Zobaer
- School of Physics, University of Sydney, Sydney, NSW, Australia
- Cooperative Research Centre for Alertness, Safety and Productivity, Melbourne, Vic., Australia
| | - Svetlana Postnova
- School of Physics, University of Sydney, Sydney, NSW, Australia
- Cooperative Research Centre for Alertness, Safety and Productivity, Melbourne, Vic., Australia
- Centre of Excellence for Integrative Brain Function, University of Sydney, Sydney, NSW, Australia
- Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia
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14
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Münch M, Wirz-Justice A, Brown SA, Kantermann T, Martiny K, Stefani O, Vetter C, Wright KP, Wulff K, Skene DJ. The Role of Daylight for Humans: Gaps in Current Knowledge. Clocks Sleep 2020; 2:61-85. [PMID: 33089192 PMCID: PMC7445840 DOI: 10.3390/clockssleep2010008] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 02/21/2020] [Indexed: 01/04/2023] Open
Abstract
Daylight stems solely from direct, scattered and reflected sunlight, and undergoes dynamic changes in irradiance and spectral power composition due to latitude, time of day, time of year and the nature of the physical environment (reflections, buildings and vegetation). Humans and their ancestors evolved under these natural day/night cycles over millions of years. Electric light, a relatively recent invention, interacts and competes with the natural light-dark cycle to impact human biology. What are the consequences of living in industrialised urban areas with much less daylight and more use of electric light, throughout the day (and at night), on general health and quality of life? In this workshop report, we have classified key gaps of knowledge in daylight research into three main groups: (I) uncertainty as to daylight quantity and quality needed for "optimal" physiological and psychological functioning, (II) lack of consensus on practical measurement and assessment methods and tools for monitoring real (day) light exposure across multiple time scales, and (III) insufficient integration and exchange of daylight knowledge bases from different disciplines. Crucial short and long-term objectives to fill these gaps are proposed.
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Affiliation(s)
- Mirjam Münch
- Sleep/Wake Research Centre, Massey University Wellington, Wellington 6021, New Zealand
| | - Anna Wirz-Justice
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, 4002 Basel, Switzerland; (A.W.-J.); (O.S.)
- Transfaculty Research Platform Molecular and Cognitive Neurosciences (MCN), University of Basel, 4002 Basel, Switzerland
| | - Steven A. Brown
- Chronobiology and Sleep Research Group, Institute of Pharmacology and Toxicology, University of Zürich, 8057 Zürich, Switzerland;
| | - Thomas Kantermann
- Faculty for Health and Social Affairs, University of Applied Sciences for Economics and Management (FOM), 45141 Essen, Germany;
- SynOpus, 44789 Bochum, Germany
| | - Klaus Martiny
- Psychiatric Center Copenhagen, University of Copenhagen, Rigshospitalet, 2100 Copenhagen, Denmark;
| | - Oliver Stefani
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, 4002 Basel, Switzerland; (A.W.-J.); (O.S.)
- Transfaculty Research Platform Molecular and Cognitive Neurosciences (MCN), University of Basel, 4002 Basel, Switzerland
| | - Céline Vetter
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; (C.V.); (K.P.W.J.)
| | - Kenneth P. Wright
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; (C.V.); (K.P.W.J.)
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado, Aurora, CO 80045, USA
| | - Katharina Wulff
- Departments of Radiation Sciences and Molecular Biology, Umeå University, 901 87 Umeå, Sweden;
- Wallenberg Centre for Molecular Medicine (WCMM), Umeå University, 901 87 Umeå, Sweden
| | - Debra J. Skene
- Chronobiology, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH, UK;
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15
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Lok R, van Koningsveld MJ, Gordijn MCM, Beersma DGM, Hut RA. Daytime melatonin and light independently affect human alertness and body temperature. J Pineal Res 2019; 67:e12583. [PMID: 31033013 PMCID: PMC6767594 DOI: 10.1111/jpi.12583] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 04/17/2019] [Accepted: 04/19/2019] [Indexed: 12/01/2022]
Abstract
Light significantly improves alertness during the night (Cajochen, Sleep Med Rev, 11, 2007 and 453; Ruger et al., AJP Regul Integr Comp Physiol, 290, 2005 and R1413), but results are less conclusive at daytime (Lok et al., J Biol Rhythms, 33, 2018 and 589). Melatonin and core body temperature levels at those times of day may contribute to differences in alerting effects of light. In this experiment, the combined effect of daytime exogenous melatonin administration and light intensity on alertness, body temperature, and skin temperature was studied. The goal was to assess whether (a) alerting effects of light are melatonin dependent, (b) soporific effects of melatonin are mediated via the thermoregulatory system, and (c) light can improve alertness after melatonin-induced sleepiness during daytime. 10 subjects (5 females, 5 males) received melatonin (5 mg) in dim (10 lux) and, on a separate occasion, in bright polychromatic white light (2000 lux). In addition, they received placebo both under dim and bright light conditions. Subjects participated in all four conditions in a balanced order, yielding a balanced within-subject design, lasting from noon to 04:00 pm. Alertness and performance were assessed half hourly, while body temperature and skin temperature were measured continuously. Saliva samples to detect melatonin concentrations were collected half hourly. Melatonin administration increased melatonin concentrations in all subjects. Subjective sleepiness and distal skin temperature increased after melatonin ingestion. Bright light exposure after melatonin administration did not change subjective alertness scores, but body temperature and proximal skin temperature increased, while distal skin temperature decreased. Light exposure did not significantly affect these parameters in the placebo condition. These results indicate that (a) exogenous melatonin administration during daytime increases subjective sleepiness, confirming a role for melatonin in sleepiness regulation, (b) bright light exposure after melatonin ingestion significantly affected thermoregulatory parameters without altering subjective sleepiness, therefore temperature changes seem nonessential for melatonin-induced sleepiness, (c) subjective sleepiness was increased by melatonin ingestion, but bright light administration was not able to improve melatonin-induced sleepiness feelings nor performance. Other (physiological) factors may therefore contribute to differences in alerting effects of light during daytime and nighttime.
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Affiliation(s)
- Renske Lok
- Chronobiology Unit, Groningen Institute for Evolutionary Life SciencesUniversity of GroningenGroningenThe Netherlands
| | - Minke J. van Koningsveld
- Chronobiology Unit, Groningen Institute for Evolutionary Life SciencesUniversity of GroningenGroningenThe Netherlands
| | - Marijke C. M. Gordijn
- Chronobiology Unit, Groningen Institute for Evolutionary Life SciencesUniversity of GroningenGroningenThe Netherlands
- Chrono@WorkGroningenThe Netherlands
| | - Domien G. M. Beersma
- Chronobiology Unit, Groningen Institute for Evolutionary Life SciencesUniversity of GroningenGroningenThe Netherlands
| | - Roelof A. Hut
- Chronobiology Unit, Groningen Institute for Evolutionary Life SciencesUniversity of GroningenGroningenThe Netherlands
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16
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de Zeeuw J, Papakonstantinou A, Nowozin C, Stotz S, Zaleska M, Hädel S, Bes F, Münch M, Kunz D. Living in Biological Darkness: Objective Sleepiness and the Pupillary Light Responses Are Affected by Different Metameric Lighting Conditions during Daytime. J Biol Rhythms 2019; 34:410-431. [PMID: 31156018 PMCID: PMC6637815 DOI: 10.1177/0748730419847845] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Nighttime melatonin suppression is the most commonly used method to indirectly quantify acute nonvisual light effects. Since light is the principal zeitgeber in humans, there is a need to assess its strength during daytime as well. This is especially important since humans evolved under natural daylight but now often spend their time indoors under artificial light, resulting in a different quality and quantity of light. We tested whether the pupillary light response (PLR) could be used as a marker for nonvisual light effects during daytime. We also recorded the wake electroencephalogram to objectively determine changes in daytime sleepiness between different illuminance levels and/or spectral compositions of light. In total, 72 participants visited the laboratory 4 times for 3-h light exposures. All participants underwent a dim-light condition and either 3 metameric daytime light exposures with different spectral compositions of polychromatic white light (100 photopic lux, peak wavelengths at 435 nm or 480 nm, enriched with longer wavelengths of light) or 3 different illuminances (200, 600, and 1200 photopic lux) with 1 metameric lighting condition (peak wavelength at 435 nm or 480 nm; 24 participants each). The results show that the PLR was sensitive to both spectral differences between metameric lighting conditions and different illuminances in a dose-responsive manner, depending on melanopic irradiance. Objective sleepiness was significantly reduced, depending on melanopic irradiance, at low illuminance (100 lux) and showed fewer differences at higher illuminance. Since many people are exposed to such low illuminance for most of their day—living in biological darkness—our results imply that optimizing the light spectrum could be important to improve daytime alertness. Our results suggest the PLR as a noninvasive physiological marker for ambient light exposure effects during daytime. These findings may be applied to assess light-dependent zeitgeber strength and evaluate lighting improvements at workplaces, schools, hospitals, and homes.
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Affiliation(s)
- Jan de Zeeuw
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Physiology, Sleep Research & Clinical Chronobiology.,Intellux GmbH, Berlin, Germany
| | - Alexandra Papakonstantinou
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Physiology, Sleep Research & Clinical Chronobiology.,St. Hedwig-Hospital, Clinic for Sleep & Chronomedicine, Berlin
| | - Claudia Nowozin
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Physiology, Sleep Research & Clinical Chronobiology.,St. Hedwig-Hospital, Clinic for Sleep & Chronomedicine, Berlin
| | - Sophia Stotz
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Physiology, Sleep Research & Clinical Chronobiology.,St. Hedwig-Hospital, Clinic for Sleep & Chronomedicine, Berlin
| | | | - Sven Hädel
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Physiology, Sleep Research & Clinical Chronobiology
| | - Frederik Bes
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Physiology, Sleep Research & Clinical Chronobiology.,St. Hedwig-Hospital, Clinic for Sleep & Chronomedicine, Berlin
| | - Mirjam Münch
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Physiology, Sleep Research & Clinical Chronobiology.,St. Hedwig-Hospital, Clinic for Sleep & Chronomedicine, Berlin.,Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Medical Immunology, Laboratory of Chronobiology.,Sleep/Wake Research Centre, Massey University, Wellington, New Zealand
| | - Dieter Kunz
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Physiology, Sleep Research & Clinical Chronobiology.,Intellux GmbH, Berlin, Germany.,St. Hedwig-Hospital, Clinic for Sleep & Chronomedicine, Berlin
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17
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Smolders KCHJ, Peeters ST, Vogels IMLC, de Kort YAW. Investigation of Dose-Response Relationships for Effects of White Light Exposure on Correlates of Alertness and Executive Control during Regular Daytime Working Hours. J Biol Rhythms 2018; 33:649-661. [PMID: 30198360 PMCID: PMC6236584 DOI: 10.1177/0748730418796438] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
To date, it is largely unknown which light settings define the optimum to steer alertness
and cognitive control during regular daytime working hours. In the current article, we
used a multimeasure approach combined with a relatively large sample size
(N = 60) and a large range of intensity levels (20-2000 lux at eye
level) to investigate the dose-dependent relationship between light and correlates of
alertness and executive control during regular working hours in the morning and afternoon.
Each participant was exposed to a single-intensity light level for 1 h after a 30-min
baseline phase (100 lux at the eye) in the morning and afternoon (on separate days) during
their daily routine. Results revealed no clear dose-dependent relationships between 1-h
daytime light exposure and correlates of alertness or executive control. Subjective
correlates showed only very modest linear relationships with the log-transformed
illuminance, and we found no significant effects of light intensity on the behavioral and
physiological indicators. Overall, these results suggest that daytime exposure to more
intense light, at least for 1 h of exposure, may not systematically benefit alertness or
executive functioning. However, future research is required to investigate effects of
longer exposure durations and potential moderations by prior light exposure, personal
characteristics, and spectrum.
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Affiliation(s)
- Karin C H J Smolders
- Human-Technology Interaction, School of Innovation Sciences, Eindhoven University of Technology, Eindhoven, the Netherlands
| | - Samantha T Peeters
- Human-Technology Interaction, School of Innovation Sciences, Eindhoven University of Technology, Eindhoven, the Netherlands
| | - Ingrid M L C Vogels
- Human-Technology Interaction, School of Innovation Sciences, Eindhoven University of Technology, Eindhoven, the Netherlands
| | - Yvonne A W de Kort
- Human-Technology Interaction, School of Innovation Sciences, Eindhoven University of Technology, Eindhoven, the Netherlands
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18
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Lok R, Smolders KCHJ, Beersma DGM, de Kort YAW. Light, Alertness, and Alerting Effects of White Light: A Literature Overview. J Biol Rhythms 2018; 33:589-601. [PMID: 30191746 PMCID: PMC6236641 DOI: 10.1177/0748730418796443] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Light is known to elicit non-image-forming responses, such as effects on alertness. This has been reported especially during light exposure at night. Nighttime results might not be translatable to the day. This article aims to provide an overview of (1) neural mechanisms regulating alertness, (2) ways of measuring and quantifying alertness, and (3) the current literature specifically regarding effects of different intensities of white light on various measures and correlates of alertness during the daytime. In general, the present literature provides inconclusive results on alerting effects of the intensity of white light during daytime, particularly for objective measures and correlates of alertness. However, the various research paradigms employed in earlier studies differed substantially, and most studies tested only a limited set of lighting conditions. Therefore, the alerting potential of exposure to more intense white light should be investigated in a systematic, dose-dependent manner with multiple correlates of alertness and within one experimental paradigm over the course of day.
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Affiliation(s)
- Renske Lok
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | - Karin C H J Smolders
- Human-Technology Interaction, School of Innovation Sciences, Eindhoven University of Technology, Eindhoven, the Netherlands
| | - Domien G M Beersma
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | - Yvonne A W de Kort
- Human-Technology Interaction, School of Innovation Sciences, Eindhoven University of Technology, Eindhoven, the Netherlands
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