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Cited by 345Circadian rhythm and melatoninImpact of Light on Environment and HealthSleep and Work-Related Fatigue

Light-at-night, circadian disruption and breast cancer: assessment of existing evidence

Open access
Stevens, R. G·2009·International Journal of Epidemiology
DOI 10.1093/ije/dyp178PMC PMC2734067
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Abstract

BACKGROUND: Breast cancer incidence is increasing globally for largely unknown reasons. The possibility that a portion of the breast cancer burden might be explained by the introduction and increasing use of electricity to light the night was suggested >20 years ago. METHODS: The theory is based on nocturnal light-induced disruption of circadian rhythms, notably reduction of melatonin synthesis. It has formed the basis for a series of predictions including that non-day shift work would increase risk, blind women would be at lower risk, long sleep duration would lower risk and community nighttime light level would co-distribute with breast cancer incidence on the population level. RESULTS: Accumulation of epidemiological evidence has accelerated in recent years, reflected in an International Agency for Research on Cancer (IARC) classification of shift work as a probable human carcinogen (2A). There is also a strong rodent model in support of the light-at-night (LAN) idea. CONCLUSION: If a consensus eventually emerges that LAN does increase risk, then the mechanisms for the effect are important to elucidate for intervention and mitigation. The basic understanding of phototransduction for the circadian system, and of the molecular genetics of circadian rhythm generation are both advancing rapidly, and will provide for the development of lighting technologies at home and at work that minimize circadian disruption, while maintaining visual efficiency and aesthetics. In the interim, there are strategies now available to reduce the potential for circadian disruption, which include extending the daily dark period, appreciate nocturnal awakening in the dark, using dim red light for nighttime necessities, and unless recommended by a physician, not taking melatonin tablets.

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  • Presence of ambient light during the night sleep is related with circadian disruptions, while a decreased health risk is related with long sleep duration and in blind women.

    “While presence of ambient light during the night sleep is related with circadian disruptions, a decreased health risk is related with long sleep duration and in blind women 95.”

    From The inner clock-Blue light sets the human rhythm (2019) · cites this paper as [95]

    The Population level section reports lower breast cancer risk in blind women and an association between long sleep duration and reduced risk in two of three prospective studies. The Introduction links light at night generally to circadian disruption, but Light in the bedroom at night says it is unclear whether low-level bedroom light meaningfully affects nocturnal melatonin production. The claim therefore states the specific ambient-light link more firmly than the source supports. (LLM, conf=0.85)

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Research works printed but not linked: 3

  1. 20 Straif K, Baan R, Grosse Y et al . Carcinogenicity of shiftwork, painting, and fire-fighting. Lancet Oncol 2007; 8: 1065-66.
  2. 61 Brainard GC, Provencio I. Photoreception for the Neurobehavioral Effects of Light in Humans . Vol. 31. CIE Light and Health Symposium II . Vienna: CIE, 2006, pp. 6-21.
  3. 73 Khaetski IK. Effect of hypothalamo-pituitary lesions induced by constant illumination on development of induced mammary tumors in rats. Vopr Exp Oncol (Kiev) 1965; 1: 87-93.

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Authors
Stevens, R. G.
Affiliations
UConn Health (US)
Corresponding author
Stevens, R. G
Venue
International Journal of Epidemiology
Publisher
Oxford University Press (OUP)
Published
2009-04-20
Volume
38
Issue
4
Pages
963-970
ISSN
  • 0300-5771 (ISSN-L)
  • 1464-3685
DOI
10.1093/ije/dyp178
PMC
PMC2734067
OpenAlex
W2127500797
Cited by
345
References
109
Citations by year
2026: 5 · 2025: 9 · 2024: 14 · 2023: 9 · 2022: 16 · 2021: 18 · 2020: 25 · 2019: 29 · 2018: 21 · 2017: 16 · 2016: 22 · 2015: 19 · 2014: 35 · 2013: 33 · 2012: 22
FWCI
11.07
Type
journal article
Language
en
Open access
Locations
  • International Journal of Epidemiology (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
National Institute of Environmental Health Sciences (ES11659, R21ES011659)
Topics
  • Life Sciences › Neuroscience › Endocrine and Autonomic Systems › Circadian rhythm and melatonin
  • Physical Sciences › Environmental Science › Global and Planetary Change › Impact of Light on Environment and Health
  • Social Sciences › Psychology › Experimental and Cognitive Psychology › Sleep and Work-Related Fatigue
Keywords
light at night, circadian rhythm disruption, breast cancer risk, nocturnal light exposure, melatonin suppression, shift work, sleep duration, circadian phototransduction, dim red light, melatonin supplementation, lighting technology
MeSH terms
Animals, Blindness, Breast Neoplasms, Circadian Rhythm, Disease Models, Animal, Female, Humans, Lighting, Melatonin, Sleep, Time Factors, Work Schedule Tolerance, Chronobiology Disorders, Light Signal Transduction

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