Table 2 Association between post-diagnosis sleep duration and mortality (N=3682)

From: Sleep and survival among women with breast cancer: 30 years of follow-up within the Nurses’ Health Study

 

Model 1

Model 2

Model 3

Hours of sleep per night (deaths/N)

HR

(95% CI)

HR

(95% CI)

HR

(95% CI)

All-cause deaths (976 deaths)

      

⩽6 h (257/965)

1.03

(0.87–1.22)

1.01

(0.86–1.20)

1.05

(0.88–1.24)

7 h (315/1234)

0.97

(0.82–1.14)

0.96

(0.82–1.13)

1.00

(0.85–1.18)

8 h (292/1100)

1 (reference)

⩾9 h (112/383)

1.45

(1.16–1.80)

1.40

(1.12–1.74)

1.37

(1.10–1.71)

P-value for non-linear trend

0.0008

0.009

0.02

Breast cancer deaths (412 deaths)

      

⩽6 h (100/965)

1.07

(0.82–1.40)

1.10

(0.84–1.44)

1.13

(0.86–1.48)

7 h (143/1234)

1.09

(0.86–1.39)

1.07

(0.84–1.36)

1.10

(0.86–1.40)

8 h (124/1100)

1 (reference)

⩾9 h (45/383)

1.49

(1.05–2.10)

1.46

(1.03–2.07)

1.46

(1.02–2.07)

P-value for non-linear trend

0.13

0.11

0.12

Non-breast cancer deaths (564 deaths)

      

⩽6 h (157/965)

1.03

(0.83–1.28)

0.98

(0.79–1.23)

1.01

(0.81–1.27)

7 h (172/1234)

0.90

(0.73–1.11)

0.89

(0.72–1.10)

0.90

(0.73–1.12)

8 h (168/1100)

1 (reference)

⩾9 h (67/383)

1.40

(1.05–1.87)

1.37

(1.03–1.83)

1.34

(1.01–1.79)

P-value for non-linear trend

0.003

0.02

0.03

  1. Abbreviations: BMI=body mass index; CI=confidence intervals; HR=hazard ratio; OC=oral contraceptive; PMH=postmenopausal hormone.
  2. Model 1: year of diagnosis, age at diagnosis, time since diagnosis, cancer stage, surgery, chemotherapy, radiation therapy, hormone therapy, prevalent diabetes or heart disease, missing indicators for oncologic treatments.
  3. Model 2: Model 1+age, marital status, education level, income, OC use, number of pregnancies, family history of breast cancer, menopausal status, PMH use.
  4. Model 3: Model 2+BMI, alcohol consumption, smoking, caffeine, calories intake, physical activity.
  5. Sample includes women who received a breast cancer diagnosis and completed either the 1986, 2000, 2002, or 2008 sleep duration assessment ⩽4 years after. Bold characters indicate statistically significant results. Italic characters indicate the reference group.
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