Delayed sleep in winter related to natural daylight exposure among Arctic day workers
Open accessAbstract
Natural daylight exposures in arctic regions vary substantially across seasons. Negative consequences have been observed in self-reports of sleep and daytime functions during the winter but have rarely been studied in detail. The focus of the present study set out to investigate sleep seasonality among indoor workers using objective and subjective measures. Sleep seasonality among daytime office workers (n = 32) in Kiruna (Sweden, 67.86° N, 20.23° E) was studied by comparing the same group of workers in a winter and summer week, including work and days off at the weekend, using actigraphs (motion loggers) and subjective ratings of alertness and mood. Actigraph analyses showed delayed sleep onset of 39 min in winter compared to the corresponding summer week (p < 0.0001) and shorter weekly sleep duration by 12 min (p = 0.0154). A delay of mid-sleep was present in winter at workdays (25 min, p < 0.0001) and more strongly delayed during days off (46 min, p < 0.0001). Sleepiness levels were higher in winter compared to summer (p < 0.05). Increased morning light exposure was associated with earlier mid-sleep (p < 0.001), while increased evening light exposure was associated with delay (p < 0.01). This study confirms earlier work that suggests that lack of natural daylight delays the sleep/wake cycle in a group of indoor workers, despite having access to electric lighting. Photic stimuli resulted in a general advanced sleep/wake rhythm during summer and increased alertness levels.
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Previous studies in humans found a correlation between latitude and chronotype variation.
“Previous studies in humans found a correlation between latitude and chronotype (morningness vs. eveningness) variation (Leocadio-Miguel et al. 2017; Randler and Rahafar 2017; Lowden et al. 2018)”
From Archaic Introgression Shaped Human Circadian Traits (2023) · cites this paper as Lowden et al. 2018
The Discussion reports seasonal shifts in sleep timing among Arctic workers and cites a finding that earlier sunrise at an Arctic latitude predicted earlier chronotype characteristics. These passages support variation in sleep timing under changing daylight, but the paper does not report a correlation between latitude and morningness–eveningness across locations. (LLM, conf=0.81)
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INDIVIDUAL LIGHT HISTORY MATTERS TO COPE WITH THE ANTARCTIC SUMMERPreprint
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- Authors
- Lowden, A., Lemos, N. A. M., Gonçalves, B. S. B., Öztürk, G., Louzada, F., Pedrazzoli, M., & Moreno, C. R.
- Affiliations
- Stress Research Institute, Stockholm University, 106 91 Stockholm, Sweden
- Stockholm University (SE)
- Universidade de São Paulo (BR)
- Universidade Federal do Paraná (BR)
- School of Arts, Science and Humanities, University of São Paulo, São Paulo 03828-000, SP, Brazil
- Venue
- Clocks & Sleep
- Publisher
- MDPI AG
- Published
- 2018-11-30
- Volume
- 1
- Issue
- 1
- Pages
- 105-116
- ISSN
- 2624-5175 (ISSN-L)
- PMC
- PMC7509675
- OpenAlex
- W2903179381
- Cited by
- 38
- References
- 36
- Citations by year
- 2026: 5 · 2025: 2 · 2024: 7 · 2023: 5 · 2022: 7 · 2021: 6 · 2020: 3 · 2019: 3
- FWCI
- 1.69
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Licence
- Locations
- Clocks & Sleep (publishedVersion, cc-by)
- PubMed Central (publishedVersion, cc-by)
- PubMed (publishedVersion)
- DiVA (Stockholm University) (submittedVersion, other-oa)
- Funders
- Forskningsrådet om Hälsa, Arbetsliv och Välfärd (2011-0488)
- Topics
- Life Sciences › Neuroscience › Endocrine and Autonomic Systems › Circadian rhythm and melatonin
- Social Sciences › Psychology › Experimental and Cognitive Psychology › Sleep and Work-Related Fatigue
- Social Sciences › Psychology › Experimental and Cognitive Psychology › Sleep and related disorders
- Keywords
- sleep onset delay, daylight exposure, circadian rhythm, indoor workers, office workers, actigraphy, sleep duration, daytime sleepiness, alertness, mood, morning light, evening light, winter
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