Research Article

Sleep Duration and Breast Cancer Phenotype

Table 2

Mean self-reported average hours of sleep per night by patient characteristic.

All patientsPremenopausalPostmenopausal
Hours of sleep per night, mean (SD) Hours of sleep per night, mean (SD) Hours of sleep per night, mean (SD)

All7.03 (1.20)N/AN/A7.08 (1.24)N/AN/A7.02 (1.20)N/AN/A
Stage0.0310.360.400.600.0260.26
 0 (DCIS)6.98 (1.20)7.11 (0.85)6.95 (1.28)
 17.14 (1.20)7.07 (1.42)7.15 (1.16)
 26.99 (1.16)7.23 (1.28)6.94 (1.13)
 36.65 (1.14)6.42 (1.17)6.67 (1.14)
 47.12 (1.68)6.00 (1.41)7.24 (1.69)
Grade0.0320.0520.0220.890.0180.049
 17.23 (1.20)7.63 (1.34)7.16 (1.17)
 27.05 (1.24)6.75 (1.27)7.11 (1.23)
 36.89 (1.18)7.27 (1.38)6.82 (1.13)
ER status0.310.710.380.880.470.69
 Positive7.04 (1.21)7.10 (1.30)7.03 (1.19)
 Negative6.94 (1.19)6.88 (0.98)6.95 (1.23)
HER2 status0.170.230.790.640.170.31
 Positive6.91 (1.10)7.00 (0.89)6.89 (1.13)
 Negative7.06 (1.21)7.09 (1.43)7.06 (1.18)

value of ANOVA (univariate); value of sleep duration in ordinal or standard logistic regression adjusted for age, race, hormone replacement therapy (HRT), family history of breast cancer, body mass index (BMI), current smoking, current alcohol consumption, and physical activity.