Figure 1.

Restricted cubic spline regression for the association between the duration of social jetlag and depressive symptoms. The solid line represents the OR and the dashed line represents the 95% CI. Knots were placed at the 10th, 50th, and 90th percentiles (0, 37.5, and 105 min, respectively) of social jetlag. The reference value was 37.5 min. The model was adjusted for age (year, continuous), sex, site, job (white-collar or blue-collar worker), job grade (low or middle and high), married (yes or no), overtime (<10, 10–29, or ≥30 h/mo), smoking status (never-smoked, former smoker, current smoker smoking <20 cigarettes/d, or current smoker smoking ≥20 cigarettes/d), alcohol consumption (nondrinker including infrequent drinker consuming alcohol less than once per week, drinker consuming <23 g of ethanol/d, drinker consuming ≥23 to <46 g of ethanol/d, or drinker consuming ≥46 g of ethanol/d), BMI (kg/m², continuous), average sleep duration on weekdays and on the weekend (hours/day, continuous), sleep quality (good, very good, not so good, or bad), flexible work (yes or no), chronotype (hours, continuous), physical activity at work (<3, 3 to <7, 7 to <20, or ≥20 METs-h/d), leisure-time physical activities (0, 0 to <3, 3 to <10, or ≥10 METs-h/wk), energy intake (kcal/day, continuous), intake of magnesium (mg/1,000 kcal, continuous), calcium (mg/1,000 kcal, continuous), iron (mg/1,000 kcal, continuous), zinc (mg/1,000 kcal, continuous), folate (µg/1,000 kcal, continuous), vitamin C (mg/1,000 kcal, continuous), vitamin B₆ (mg/1,000 kcal, continuous), vitamin B₁₂ (µg/1,000 kcal, continuous), ω-3 PUFA (% energy, continuous).