Table 5.

Adjusted RR for measures of sleep for all breast cancer combined and for ER+ breast cancer only

CasesControlsRR (95% CI)PtrendRR (95% CI)aPtrend
All cases
 Sleep duration
  <6 h881701.0 (ref.)0.741.0 (ref.)0.70
  7 h1072110.99 (0.70–1.42)1.00 (0.68–1.47)
  ≥8 h631320.93 (0.62–1.38)0.91 (0.59–1.41)
 Insomnia
  No insomnia1773541.0 (ref.)0.731.0 (ref.)0.72
  Insomnia771481.06 (0.76–1.47)0.93 (0.65–1.34)
ER+ cases
 Sleep duration
  <6 h581151.0 (ref.)0.981.0 (ref.)0.67
  7 h711391.02 (0.66–1.59)0.96 (0.60–1.54)
  ≥8 h47960.99 (0.61–1.60)0.89 (0.53–1.50)
 Insomnia
  No insomnia1292381.0 (ref.)0.321.0 (ref.)0.28
  Insomnia451040.81 (0.54–1.22)0.83 (0.54–1.28)

Abbreviation: RR, relative risk.

  • aAdjusted for education, bilateral oophorectomy, and first-degree relative with breast cancer.