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Author (up) Johns, L.E.; Jones, M.E.; Schoemaker, M.J.; McFadden, E.; Ashworth, A.; Swerdlow, A.J. url  doi
openurl 
  Title Domestic light at night and breast cancer risk: a prospective analysis of 105 000 UK women in the Generations Study Type Journal Article
  Year 2018 Publication British Journal of Cancer Abbreviated Journal Br J Cancer  
  Volume 118 Issue Pages 600-606  
  Keywords Human Health  
  Abstract BACKGROUND: Circadian disruption caused by exposure to light at night (LAN) has been proposed as a risk factor for breast cancer and a reason for secular increases in incidence. Studies to date have largely been ecological or case-control in design and findings have been mixed. METHODS: We investigated the relationship between LAN and breast cancer risk in the UK Generations Study. Bedroom light levels and sleeping patterns at age 20 and at study recruitment were obtained by questionnaire. Analyses were conducted on 105 866 participants with no prior history of breast cancer. During an average of 6.1 years of follow-up, 1775 cases of breast cancer were diagnosed. Cox proportional hazard models were used to calculate hazard ratios (HRs), adjusting for potential confounding factors. RESULTS: There was no association between LAN level and breast cancer risk overall (highest compared with lowest LAN level at recruitment: HR=1.01, 95% confidence interval (CI): 0.88-1.15), or for invasive (HR=0.98, 95% CI: 0.85-1.13) or in situ (HR=0.96, 95% CI: 0.83-1.11) breast cancer, or oestrogen-receptor (ER) positive (HR=0.98, 95% CI: 0.84-1.14); or negative (HR=1.16, 95% CI: 0.82-1.65) tumours separately. The findings did not differ by menopausal status. Adjusting for sleep duration, sleeping at unusual times (non-peak sleep) and history of night work did not affect the results. Night waking with exposure to light, occurring around age 20, was associated with a reduced risk of premenopausal breast cancer (HR for breast cancer overall=0.74, 95% CI: 0.55-0.99; HR for ER-positive breast cancer=0.69, 95% CI: 0.49-0.97). CONCLUSIONS: In this prospective cohort analysis of LAN, there was no evidence that LAN exposure increased the risk of subsequent breast cancer, although the suggestion of a lower breast cancer risk in pre-menopausal women with a history of night waking in their twenties may warrant further investigation.British Journal of Cancer advance online publication, 23 January 2018; doi:10.1038/bjc.2017.359 www.bjcancer.com.  
  Address Division of Breast Cancer Research, The Institute of Cancer Research, London SW3 6JB, UK  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0007-0920 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:29360812 Approved no  
  Call Number LoNNe @ kyba @ Serial 1803  
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Author (up) McFadden, E.; Jones, M.E.; Schoemaker, M.J.; Ashworth, A.; Swerdlow, A.J. url  doi
openurl 
  Title The Relationship Between Obesity and Exposure to Light at Night: Cross-Sectional Analyses of Over 100,000 Women in the Breakthrough Generations Study Type Journal Article
  Year 2014 Publication American Journal of Epidemiology Abbreviated Journal Am J Epidemiol  
  Volume 180 Issue 3 Pages 245-250  
  Keywords body mass index; circadian rhythm; light at night; obesity; sleep; sleeping habits  
  Abstract There has been a worldwide epidemic of obesity in recent decades. In animal studies, there is convincing evidence that light exposure causes weight gain, even when calorie intake and physical activity are held constant. Disruption of sleep and circadian rhythms by exposure to light at night (LAN) might be one mechanism contributing to the rise in obesity, but it has not been well-investigated in humans. Using multinomial logistic regression, we examined the association between exposure to LAN and obesity in questionnaire data from over 100,000 women in the Breakthrough Generations Study, a cohort study of women aged 16 years or older who were living in the United Kingdom and recruited during 2003-2012. The odds of obesity, measured using body mass index, waist:hip ratio, waist:height ratio, and waist circumference, increased with increasing levels of LAN exposure (P < 0.001), even after adjustment for potential confounders such as sleep duration, alcohol intake, physical activity, and current smoking. We found a significant association between LAN exposure and obesity which was not explained by potential confounders we could measure. While the possibility of residual confounding cannot be excluded, the pattern is intriguing, accords with the results of animal experiments, and warrants further investigation.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0002-9262 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:24875371 Approved no  
  Call Number IDA @ john @ Serial 166  
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