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Sleep characteristics, light at night and breast cancer risk in a prospective cohort
Author(s) -
White Alexandra J.,
Weinberg Clarice R.,
Park YongMoon,
D'Aloisio Aimee A.,
Vogtmann Emily,
Nichols Hazel B.,
Sandler Dale P.
Publication year - 2017
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.30920
Subject(s) - medicine , breast cancer , hazard ratio , prospective cohort study , cohort , proportional hazards model , cohort study , cancer , sleep (system call) , confidence interval , gynecology , oncology , computer science , operating system
Increasing numbers of women in the US are getting too little sleep. Inadequate sleep has been associated with impaired metabolic function and endocrine disruption. Sister Study cohort participants ( n = 50,884), completed baseline and follow‐up questionnaires on sleep patterns. Incident breast cancers estrogen receptor (ER) status of the tumor were ascertained from questionnaires and medical records. Cox regression was used to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (95% CIs). Analyses of sleep characteristics reported at the first follow‐up interview included only participants who were breast cancer‐free at time of follow‐up interview. Over ∼7 years of follow‐up, 2,736 breast cancer cases (invasive and ductal carcinoma in situ ) were diagnosed. There was little evidence that usual sleep duration or other sleep characteristics were associated with breast cancer. However, relative to those with no difficulty sleeping, women who reported having difficulty sleeping ≥ 4 nights a week were at an increased risk of overall (HR = 1.32, 95% CI: 1.09–1.61) and postmenopausal breast cancer (HR = 1.51, 95% CI 1.24–1.85). Risk of ER+ invasive cancer was elevated for women who reported having a light or television on in the room while sleeping (HR = 1.20, 95% CI: 0.97–1.47) or who typically got less sleep than they needed to feel their best (HR = 1.21, 95% CI: 0.98–1.50). In our study, most sleep characteristics, including sleep duration, were not associated with an increased risk although higher risk was observed for some markers of inadequate or poor quality sleep.