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Amdisen L, Daugaard S, Vestergaard JM, Vested A, Bonde JP, Vistisen HT, Christoffersen J, Garde AH, Hansen ÅM, Markvart J, Schlünssen V, Kolstad HA. A longitudinal study of morning, evening, and night light intensities and nocturnal sleep quality in a working population. Chronobiol Int 2021; 39:579-589. [PMID: 34903140 DOI: 10.1080/07420528.2021.2010741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
We aimed to investigate whether higher light intensity in the morning is associated with better nocturnal sleep quality and whether higher light intensities in the evening or night have the opposite effect. Light intensity was recorded for 7 consecutive days across the year among 317 indoor and outdoor daytime workers in Denmark (55-56° N) equipped with a personal light recorder. Participants reported sleep quality after each nocturnal sleep. Sleep quality was measured using three parameters; disturbed sleep index, awakening index, and sleep onset latency. Associations between increasing light intensities and sleep quality were analyzed using mixed effects models with participant identity as a random effect. Overall, neither white nor blue light intensities during morning, evening, or night were associated with sleep quality, awakening, or sleep onset latency of the subsequent nocturnal sleep. However, secondary analyses suggested that artificial light during the morning and day contrary to solar light may increase vulnerability to evening light exposure. Altogether, we were not able to confirm that higher morning light intensity significantly improves self-reported sleep quality or that higher evening or night light intensities impair self-reported sleep quality at exposure levels encountered during daily life in a working population in Denmark. This suggests that light intensities alone are not important for sleep quality to a degree that it is distinguishable from other important parameters in daily life settings.
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Affiliation(s)
- Lau Amdisen
- Department of Occupational Medicine, Danish Ramazzini Centre, Aarhus University Hospital, Aarhus, Denmark
| | - Stine Daugaard
- Department of Occupational Medicine, Danish Ramazzini Centre, Aarhus University Hospital, Aarhus, Denmark
| | - Jesper Medom Vestergaard
- Department of Occupational Medicine, Danish Ramazzini Centre, Aarhus University Hospital, Aarhus, Denmark.,Department of Occupational Medicine, Danish Ramazzini Centre, University Research Clinic, Herning, Denmark
| | - Anne Vested
- Department of Occupational Medicine, Danish Ramazzini Centre, Aarhus University Hospital, Aarhus, Denmark
| | - Jens Peter Bonde
- Department of Occupational and Environmental Medicine, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark.,Department of Public Health, Section of Social Medicine, Institute of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - Helene Tilma Vistisen
- Department of Occupational Medicine, Danish Ramazzini Centre, Aarhus University Hospital, Aarhus, Denmark
| | - Jens Christoffersen
- Knowledge Centre for Daylight, Energy and Indoor Climate, Velux A/s, Velux Group, Hørsholm, Denmark
| | - Anne Helene Garde
- Danish Ministry of Employment, National Research Centre for the Working Environment, Copenhagen, Denmark
| | - Åse Marie Hansen
- Department of Public Health, Section of Social Medicine, Institute of Public Health, University of Copenhagen, Copenhagen, Denmark.,Danish Ministry of Employment, National Research Centre for the Working Environment, Copenhagen, Denmark
| | - Jakob Markvart
- Department of the Built Environment, Division of Energy Efficiency, Indoor Climate and Sustainability of Buildings, Aalborg University, Copenhagen, Denmark
| | - Vivi Schlünssen
- Department of Public Health, Environment, Occupation and Health, Danish Ramazzini Centre, Aarhus University, Aarhus, Denmark
| | - Henrik Albert Kolstad
- Department of Occupational Medicine, Danish Ramazzini Centre, Aarhus University Hospital, Aarhus, Denmark
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