Table 6.
Association between sleep during preconception and neonatal irritability in the Japan Environment and Children’s Study (2011–2014).
| No. of participants | Outcome | Maternal age-adjusted model | Multivariable modela | ||||||
|---|---|---|---|---|---|---|---|---|---|
| No. | % | RR | 95% CI | RR | 95% CI | ||||
| Bad mood | |||||||||
| Sleep time (h) | |||||||||
| < 6 | 5,603 | 469 | 8.4 | 1.33 | 1.21 | 1.47 | 1.12 | 1.01 | 1.23 |
| 6–7 | 16,142 | 1,278 | 7.9 | 1.26 | 1.17 | 1.35 | 1.09 | 1.01 | 1.16 |
| 7–8 | 27,584 | 1,735 | 6.3 | Reference | Reference | ||||
| 8–9 | 20,238 | 966 | 4.8 | 0.76 | 0.70 | 0.82 | 0.97 | 0.90 | 1.05 |
| 9–10 | 8,308 | 356 | 4.3 | 0.68 | 0.61 | 0.76 | 1.05 | 0.94 | 1.17 |
| > 10 | 3,804 | 239 | 6.3 | 1.00 | 0.87 | 1.14 | 1.17 | 1.02 | 1.33 |
| Bedtime | |||||||||
| 21:00–24:00 | 54,935 | 2,803 | 5.1 | Reference | Reference | ||||
| 24:00–03:00 | 24,434 | 2,084 | 8.5 | 1.68 | 1.59 | 1.77 | 1.12 | 1.06 | 1.19 |
| Other | 2,310 | 156 | 6.8 | 1.35 | 1.15 | 1.57 | 1.10 | 0.94 | 1.29 |
| Frequent crying, for long periods | |||||||||
| Sleep time (h) | |||||||||
| < 6 | 5,587 | 1,255 | 22.5 | 1.28 | 1.21 | 1.35 | 1.17 | 1.11 | 1.24 |
| 6–7 | 16,093 | 3,332 | 20.7 | 1.18 | 1.14 | 1.23 | 1.09 | 1.05 | 1.13 |
| 7–8 | 27,534 | 4,810 | 17.5 | Reference | Reference | ||||
| 8–9 | 20,205 | 3,013 | 14.9 | 0.85 | 0.82 | 0.89 | 0.98 | 0.94 | 1.02 |
| 9–10 | 8,299 | 1,066 | 12.8 | 0.74 | 0.69 | 0.78 | 0.91 | 0.86 | 0.97 |
| > 10 | 3,800 | 619 | 16.3 | 0.94 | 0.87 | 1.01 | 1.01 | 0.94 | 1.09 |
| Bedtime | |||||||||
| 21:00–24:00 | 54,840 | 8,530 | 15.6 | Reference | Reference | ||||
| 24:00–03:00 | 24,365 | 5,178 | 21.3 | 1.38 | 1.33 | 1.42 | 1.09 | 1.06 | 1.13 |
| Other | 2,313 | 387 | 16.7 | 1.09 | 1.00 | 1.20 | 0.96 | 0.88 | 1.06 |
| Intense crying | |||||||||
| Sleep time (h) | |||||||||
| < 6 | 5,592 | 1,448 | 25.9 | 1.30 | 1.23 | 1.36 | 1.15 | 1.09 | 1.20 |
| 6–7 | 16,114 | 3,886 | 24.1 | 1.21 | 1.17 | 1.25 | 1.08 | 1.04 | 1.12 |
| 7–8 | 27,546 | 5,490 | 19.9 | Reference | Reference | ||||
| 8–9 | 20,201 | 3,234 | 16.0 | 0.80 | 0.77 | 0.84 | 0.97 | 0.93 | 1.01 |
| 9–10 | 8,295 | 1,149 | 13.9 | 0.69 | 0.65 | 0.74 | 0.95 | 0.89 | 1.00 |
| > 10 | 3,800 | 671 | 17.7 | 0.88 | 0.81 | 0.94 | 0.98 | 0.91 | 1.06 |
| Bedtime | |||||||||
| 21:00–24:00 | 54,833 | 9,350 | 17.1 | Reference | Reference | ||||
| 24:00–03:00 | 24,402 | 6,082 | 24.9 | 1.46 | 1.42 | 1.51 | 1.07 | 1.04 | 1.10 |
| Other | 2,313 | 446 | 19.3 | 1.14 | 1.04 | 1.24 | 0.97 | 0.89 | 1.05 |
CI, confidence interval; RR, relative risk.
aAdjusted for maternal age at delivery, smoking habits, alcohol consumption, pre-pregnancy body mass index, gestational age at birth, parity, infertility treatment, infant sex, small for gestational age, type of delivery, and postpartum depressive symptoms.