title: Sleep duration and breast cancer prognosis: perspectives from the Women's Healthy Eating and Living Study.
abstract: To examine whether baseline sleep duration or changes in sleep duration are associated with breast cancer prognosis among early-stage breast cancer survivors in the multi-center Women's Healthy Eating and Living Study.
  
  
  
  Data were collected from 1995 to 2010. Analysis included 3047 women. Sleep duration was self-reported at baseline and follow-up intervals. Cox proportional hazard models were used to investigate whether baseline sleep duration was associated with breast cancer recurrence, breast cancer-specific mortality, and all-cause mortality. Time-varying models investigated whether changes in sleep duration were associated with breast cancer prognosis.
  
  
  
  Compared to women who slept 7-8 h/night at baseline, sleeping ≥9 h/night was associated with a 48% increased risk of breast cancer recurrence (Hazard ratio [HR] 1.48, 95% Confidence interval [CI] 1.01, 2.00), a 52% increased risk of breast cancer-specific mortality (HR 1.52, 95% CI 1.09, 2.13), and a 43% greater risk of all-cause mortality (HR 1.43, 95% CI 1.07, 1.92). Time-varying models showed analogous increased risk in those who inconsistently slept ≥9 h/night (all P < 0.05), but not in those who consistently slept ≥9 h/night.
  
  
  
  Consistent long or short sleep, which may reflect inter-individual variability in the need for sleep, does not appear to influence prognosis among early-stage breast cancer survivors.
authors.affiliation: Dana-Farber Cancer Institute, 450 Brookline Ave, Boston, MA, USA. CatherineR_Marinac@dfci.harvard.edu.|Harvard TH Chan School of Public Health, Boston, MA, USA. CatherineR_Marinac@dfci.harvard.edu.|Department of Family Medicine and Public Health, University of California, San Diego, La Jolla, CA, USA. CatherineR_Marinac@dfci.harvard.edu.
authors.forename: Catherine R
authors.initials: CR
authors.lastname: Marinac
authors.affiliation: Department of Family Medicine and Public Health, University of California, San Diego, La Jolla, CA, USA.|Moores Cancer Center, University of California, San Diego, La Jolla, CA, USA.|Graduate School of Public Health, San Diego State University, San Diego, CA, USA.
authors.forename: Sandahl H
authors.initials: SH
authors.lastname: Nelson
authors.affiliation: Moores Cancer Center, University of California, San Diego, La Jolla, CA, USA.
authors.forename: Shirley W
authors.initials: SW
authors.lastname: Flatt
authors.affiliation: Department of Family Medicine and Public Health, University of California, San Diego, La Jolla, CA, USA.|Moores Cancer Center, University of California, San Diego, La Jolla, CA, USA.
authors.forename: Loki
authors.initials: L
authors.lastname: Natarajan
authors.affiliation: Department of Family Medicine and Public Health, University of California, San Diego, La Jolla, CA, USA.|Moores Cancer Center, University of California, San Diego, La Jolla, CA, USA.
authors.forename: John P
authors.initials: JP
authors.lastname: Pierce
authors.affiliation: Department of Family Medicine and Public Health, University of California, San Diego, La Jolla, CA, USA.|Moores Cancer Center, University of California, San Diego, La Jolla, CA, USA.
authors.forename: Ruth E
authors.initials: RE
authors.lastname: Patterson
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000401:mortality / Q000473:pathology / Q000628:therapy; D000073116:Cancer Survivors; D003131:Combined Modality Therapy; D000072001:Diet, Healthy; D005260:Female; D006801:Humans; D008019:Life Style; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D011379:Prognosis; D012307:Risk Factors; D057566:Self Report; D012890:Sleep
keywords: Longitudinal modeling; Sleep; Survival; Survivorship