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Sleep duration and breast cancer risk: A meta‐analysis of observational studies
Author(s) -
Qin Yingyi,
Zhou Yuhao,
Zhang Xiao,
Wei Xin,
He Jia
Publication year - 2013
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.28452
Subject(s) - medicine , meta analysis , breast cancer , odds ratio , confidence interval , confounding , observational study , cohort study , subgroup analysis , relative risk , incidence (geometry) , publication bias , oncology , cancer , physics , optics
Studies on the association of short or long sleep duration with breast cancer risk have reported inconsistent results. We quantitatively assessed this association by conducting a meta‐analysis based on the evidence from observational studies. In April 2013, we performed electronic searches in PubMed, EmBase and the Cochrane Library to identify studies examining the effect of sleep duration on breast cancer incidence. The odds ratio (OR) was used to measure any such association in a random‐effects model. The analysis was further stratified by confounding factors that could bias the results. A total of six studies (two case–control and four cohort studies) involving 159,837 individuals were included in our meta‐analysis. Our study did not show an association between either short or long sleep duration and breast cancer risk (short sleep duration data: pooled OR = 1.01, 95% confidence interval (CI) = 0.90–1.14, p = 0.853; long sleep duration data: pooled OR = 0.95, 95% CI = 0.86–1.04, p = 0.251). Moreover, we did not identify any statistically significant association between sleep duration and breast cancer risk in all the subgroup analyses. In conclusion, our findings indicate that sleep duration has no effect on breast cancer risk.