Table 2.
Association of Chronotype and Incident Depression in the Nurses’ Health Study II (N=32,470, 2009–2013). HR= Hazard Ratios, 95%CI= 95% confidence intervals. MV=multivariable, HR=Hazard Ratio, CI=confidence interval.
| Cases | Person/years | Age-adjusted Model | MV Model* | |||
|---|---|---|---|---|---|---|
| HR | 95% CI | HR | 95% CI | |||
| Chronotype | ||||||
| Early type | 872 | 44,483 | 0.86 | 0.79, 0.93 | 0.88 | 0.81, 0.96 |
| Intermediate type | 1,419 | 61,411 | 1.00 (ref) | 1.00 (ref) | ||
| Late type | 290 | 11,164 | 1.13 | 1.00, 1.29 | 1.06 | 0.93, 1.20 |
| ptrend# < 0.0001 | ptrend# = 0.0009 | |||||
| Sensitivity analysis restricting to women who usually slept 7–8h/day in 2001 and 2009 (N=17,702, 2009–2013) | ||||||
| Early type | 510 | 25,296 | 0.92 | 0.82, 1.03 | 0.94 | 0.84, 1.06 |
| Intermediate type | 756 | 33,967 | 1.00 (ref) | 1.00 (ref) | ||
| Late type | 126 | 4,862 | 1.19 | 0.98, 1.44 | 1.13 | 0.93, 1.37 |
| ptrend# = 0.02 | ptrend# = 0.08 | |||||
| Sensitivity analysis restricting to women, who never worked shiftwork (N=9,701) | ||||||
| Early type | 231 | 13,330 | 0.73 | 0.62, 0.85 | 0.73 | 0.62, 0.86 |
| Intermediate type | 440 | 18,749 | 1.00 (ref) | 1.00 (ref) | ||
| Late type | 71 | 3,021 | 1.00 | 0.78, 1.29 | 0.94 | 0.72, 1.21 |
| ptrend# = 0.0003 | ptrend# = 0.002 | |||||
Adjusted for menopausal status (pre/post-menopausal), marriage (never married/married or partnership/was married), living situation (living alone/living with partner or kids), census-tract based household income (in tertiles), retirement status (retired, yes/no), smoking status (never smoker, past light/moderate smoker [1–24 cigs per day], past heavy smoker ≥ 25 cigs per day, past smoker with unknown no. of cigs, current light/moderate smoker [1–24 cigs per day], current heavy smoker [≥25 cigs per day] or current smoker with unknown no. of cigs), physical activity (in quintiles), body mass index (≤25, >25 but <30, ≥30 kg per m2), sleep duration (≤5/6/7/8/≥9h per day), predicted Vitamin D levels (in quintiles), alcohol consumption (0, 0.1–4.9, 5.0–14.9, ≥15g/day), cancer (yes/no), myocardial infarction (yes/no), type 2 diabetes (yes/no).
P-values for trends are based on a linear trend test using chronotype continuously (early =1, intermediate=2, and late =3).