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Eto T, Kitamura S, Nishimura K, Takeoka K, Nishimura Y, Lee SI, Ohashi M, Shikano A, Noi S, Higuchi S. Circadian phase advances in children during camping life according to the natural light-dark cycle. J Physiol Anthropol 2022; 41:42. [PMID: 36527162 PMCID: PMC9756595 DOI: 10.1186/s40101-022-00316-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Accepted: 12/06/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND It is known that the circadian rhythm phase in adults can be advanced in a natural light-dark cycle without electrical lighting. However, the effect of advanced sleep-wake timing according to the natural light-dark cycle on children's circadian phase is unclear. We investigated the effects of approximately 2 weeks of camping life with little access to artificial lighting on children's circadian phases. We also conducted an exploratory examination on the effects of wake time according to natural sunrise time on the manner of the advance of their circadian phases. METHODS Twenty-one healthy children (mean ± SD age, 10.6 ± 1.4 years) participated in a camping program with wake time (4:00) being earlier than sunrise time (EW condition), and 21 healthy children (10.4 ± 1.1 years) participated in a camping program with wake time (5:00) being almost matched to sunrise time (SW condition). Salivary dim light melatonin onset (DLMO) before the camping program and that after approximately 2 weeks of camping were compared. RESULTS DLMO was advanced by approximately 2 h after the camping program compared with the circadian phase in daily life in both conditions. In addition, the advances in DLMO were significantly correlated with mid-sleep points before the camp in both conditions (EW: r = 0.72, p < 0.01, SW: r = 0.70, p < 0.01). These correlations mean that the phase advance was greater for the children with delayed sleep habits in daily life. Furthermore, in the EW condition, mean DLMO after the camp (18:09 ± 0:33 h) was earlier than natural sunset time and there was no significant decrease in interindividual variability in DLMO. On the other hand, in the SW condition, mean DLMO after the camp (18:43 ± 0:20 h) matched natural sunset time and interindividual variability in DLMO was significantly lower than that before the camp. CONCLUSIONS Camping with advanced sleep and wake timing under natural sunlight advances children's circadian phases. However, DLMO earlier than sunset in an early waking condition may lead to large interindividual variability in the circadian rhythm phase.
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Affiliation(s)
- Taisuke Eto
- grid.177174.30000 0001 2242 4849Graduate School of Integrated Frontier Sciences, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan ,grid.177174.30000 0001 2242 4849Department of Human Science, Faculty of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan ,Research Fellow of the Japan Society for the Promotion of Science, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan ,grid.416859.70000 0000 9832 2227Department of Sleep-Wake Disorders, National Institute of Mental Health, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo, 187-8553 Japan
| | - Shingo Kitamura
- grid.416859.70000 0000 9832 2227Department of Sleep-Wake Disorders, National Institute of Mental Health, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo, 187-8553 Japan
| | - Kana Nishimura
- grid.177174.30000 0001 2242 4849Graduate School of Integrated Frontier Sciences, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan
| | - Kota Takeoka
- grid.177174.30000 0001 2242 4849Graduate School of Integrated Frontier Sciences, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan
| | - Yuki Nishimura
- grid.177174.30000 0001 2242 4849Graduate School of Integrated Frontier Sciences, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan ,grid.415747.4Occupational Stress and Health Management Research Group, National Institute of Occupational Safety and Health, 6-21-1 Nagao, Tama-ku, Kawasaki, Kanagawa 214-8585 Japan
| | - Sang-il Lee
- grid.177174.30000 0001 2242 4849Department of Human Science, Faculty of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan ,grid.39158.360000 0001 2173 7691Laboratory of Environmental Ergonomics, Faculty of Engineering, Hokkaido University, Kita 13, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628 Japan
| | - Michihiro Ohashi
- grid.177174.30000 0001 2242 4849Graduate School of Integrated Frontier Sciences, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan ,Research Fellow of the Japan Society for the Promotion of Science, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan
| | - Akiko Shikano
- grid.412200.50000 0001 2228 003XFaculty of Sport Science, Nippon Sport Science University, 7-1-1 Fukasawa, Setagaya-ku, Tokyo, 158-8508 Japan
| | - Shingo Noi
- grid.412200.50000 0001 2228 003XFaculty of Sport Science, Nippon Sport Science University, 7-1-1 Fukasawa, Setagaya-ku, Tokyo, 158-8508 Japan
| | - Shigekazu Higuchi
- grid.177174.30000 0001 2242 4849Department of Human Science, Faculty of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan
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Giménez MC, Stefani O, Cajochen C, Lang D, Deuring G, Schlangen LJM. Predicting melatonin suppression by light in humans: Unifying photoreceptor-based equivalent daylight illuminances, spectral composition, timing and duration of light exposure. J Pineal Res 2022; 72:e12786. [PMID: 34981572 PMCID: PMC9285453 DOI: 10.1111/jpi.12786] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 12/30/2021] [Accepted: 12/30/2021] [Indexed: 12/23/2022]
Abstract
Light-induced melatonin suppression data from 29 peer-reviewed publications was analysed by means of a machine-learning approach to establish which light exposure characteristics (ie photopic illuminance, five α-opic equivalent daylight illuminances [EDIs], duration and timing of the light exposure, and the dichotomous variables pharmacological pupil dilation and narrowband light source) are the main determinants of melatonin suppression. Melatonin suppression in the data set was dominated by four light exposure characteristics: (1) melanopic EDI, (2) light exposure duration, (3) pupil dilation and (4) S-cone-opic EDI. A logistic model was used to evaluate the influence of each of these parameters on the melatonin suppression response. The final logistic model was only based on the first three parameters, since melanopic EDI was the best single (photoreceptor) predictor that was only outperformed by S-cone-opic EDI for (photopic) illuminances below 21 lux. This confirms and extends findings on the importance of the metric melanopic EDI for predicting biological effects of light in integrative (human-centric) lighting applications. The model provides initial and general guidance to lighting practitioners on how to combine spectrum, duration and amount of light exposure when controlling non-visual responses to light, especially melatonin suppression. The model is a starting tool for developing hypotheses on photoreceptors' contributions to light's non-visual responses and helps identifying areas where more data are needed, like on the S-cone contribution at low illuminances.
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Affiliation(s)
- Marina C. Giménez
- Chronobiology UnitGroningen Institute for Evolutionary Life SciencesUniversity of GroningenGroningenThe Netherlands
| | - Oliver Stefani
- Centre for Chronobiology and Transfaculty Research Platform Molecular and Cognitive Neurosciences (MCN)Psychiatric Hospital of the University of Basel (UPK) and University of BaselBaselSwitzerland
| | - Christian Cajochen
- Centre for Chronobiology and Transfaculty Research Platform Molecular and Cognitive Neurosciences (MCN)Psychiatric Hospital of the University of Basel (UPK) and University of BaselBaselSwitzerland
| | | | - Gunnar Deuring
- Forensic DepartmentUniversity Psychiatric Clinics BaselBaselSwitzerland
| | - Luc J. M. Schlangen
- Department of Industrial Engineering and Innovation SciencesHuman‐Technology Interaction Group and Intelligent Lighting InstituteEindhoven University of TechnologyEindhovenThe Netherlands
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Lam C, Chung MH. Dose-response effects of light therapy on sleepiness and circadian phase shift in shift workers: a meta-analysis and moderator analysis. Sci Rep 2021; 11:11976. [PMID: 34099750 PMCID: PMC8184774 DOI: 10.1038/s41598-021-89321-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 04/13/2021] [Indexed: 11/09/2022] Open
Abstract
Light therapy has been considered to be effective in mitigating sleepiness and regulating circadian phase shift in shift workers. However, the effective treatment dose of light therapy remains undetermined. We performed a meta-analysis of randomized experimental studies to determine the effect of light therapy doses on sleepiness and circadian phase shift in shift workers. An article search was performed in 10 electronic databases from inception to June 2020. Two raters independently screened and extracted data and reached consensus. Twenty-one eligible studies were included. Analyses were performed using random-effects models. Light therapy exerted significantly small to medium effects on sleepiness and large treatment effects on circadian phase shift. Moderator analyses performed with subgroup and metaregression analyses revealed that medium-intensity light therapy for a shorter duration more effectively reduced sleepiness at night, whereas higher-intensity light therapy more effectively induced phase shifting, but the required treatment duration remained inconclusive. This study provides evidence regarding the effect of light therapy in reducing sleepiness and shifting circadian phase in shift workers. Exposure to medium-intensity light for a short duration at night reduced sleepiness, whereas exposure to high-intensity light improved sleep by shifting their circadian phase.
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Affiliation(s)
- Calvin Lam
- Department of Psychology, The University of Hong Kong, Pok Fu Lam, Hong Kong
| | - Min-Huey Chung
- School of Nursing, College of Nursing, Taipei Medical University, Taipei, Taiwan. .,Department of Nursing, Shuang Ho Hospital, Taipei Medical University, New Taipei City, Taiwan.
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