Table 3.
Multivariable linear mixed-effects model estimates of monthly changes in height and height SDS from 1.5 to 3 years of age according to sleep characteristics, with adjustment for demographic and socioeconomic factors.
| Multivariable model | Height B (×10−3 cm/month) | p-value | ||
|---|---|---|---|---|
| Categorical sleep duration (≥ 10 h vs. < 10 h) |
p-value | Continuous sleep duration (per hour) | ||
| Sleep duration | 1.45 (−1.82, 4.71) | 0.385 | 2.47 (0.69, 4.25) | 0.006 |
| Bedtime (20:00–21:59 vs. ≥ 22:00) |
7.21 (3.26, 11.15) | <0.001 | 5.40 (1.34, 9.46) | 0.009 |
| Nighttime awakenings (< 3 vs. ≥ 3) |
6.49 (−3.97, 16.95) | 0.222 | 3.50 (−7.14, 14.14) | 0.519 |
| Sex (male vs. female) | −13.29 (−16.11, −10.46) | <0.001 | −13.22 (−16.04, −10.39) | < 0.001 |
| Maternal height SDS | 16.38 (14.94, 17.81) | <0.001 | 16.37 (14.93, 17.80) | < 0.001 |
| Paternal height SDS | 16.27 (14.81, 17.72) | <0.001 | 16.25 (14.80, 17.71) | < 0.001 |
| Maternal education status (post-secondary education vs. ≤ senior high school) | 3.32 (0.03, 6.60) | 0.048 | 3.32 (0.03, 6.60) | 0.048 |
| Paternal education status (post-secondary education vs. ≤ senior high school) | −1.01 (−4.09, 2.07) | 0.520 | −1.06 (−4.14, 2.01) | 0.499 |
| Annual household income (≥ 6 million yen vs. < 6 million yen) | −2.39 (−5.68, 0.89) | 0.153 | −2.30 (−5.59, 0.98) | 0.169 |
| Worker (multi-earner households vs. single-earner households) | 3.01 (0.00, 6.01) | 0.049 | 3.33 (0.32, 6.34) | 0.030 |
| Height SDS B (×10−3 SD/month) | |||
|---|---|---|---|
| Categorical sleep duration (≥ 10 h vs. < 10 h) |
p-value | Continuous sleep duration (per hour) | p-value |
| −0.34 (−1.19, 0.51) | 0.436 | 0.02 (−0.44, 0.48) | 0.944 |
| 2.53 (1.51, 3.56) | <0.001 | 2.36 (1.31, 3.42) | <0.001 |
| 2.62 (−0.09, 5.34) | 0.058 | 2.39 (−0.38, 5.16) | 0.091 |
| −3.60 (−4.34, −2.87) | <0.001 | −3.60 (−4.33, −2.86) | <0.001 |
| 2.17 (1.79, 2.54) | <0.001 | 2.17 (1.79, 2.54) | <0.001 |
| 2.36 (1.98, 2.74) | <0.001 | 2.36 (1.98, 2.73) | <0.001 |
| 2.41 (1.56, 3.27) | <0.001 | 2.41 (1.56, 3.27) | <0.001 |
| 0.53 (− 0.27, 1.33) | 0.191 | 0.53 (−0.27, 1.33) | 0.193 |
| 0.13 (−0.72, 0.99) | 0.760 | 0.14 (−0.71, 1.00) | 0.744 |
| 3.72 (2.94, 4.54) | <0.001 | 3.75 (2.97, 4.50) | <0.001 |
B, regression coefficient; CI, confidence interval; SDS, standard deviation score. Data are presented as estimates (B) with 95% confidence intervals (CIs) in parentheses. Estimates represent the monthly change in height or height SDS. The multivariable model was simultaneously adjusted for all variables listed in the table, including sleep duration, bedtime, nighttime awakenings, sex, maternal height SDS, paternal height SDS, maternal education status, paternal education status, annual household income, and number of household earners. For categorical variables, estimates represent the difference between the indicated group and the reference group, with comparisons shown as [target group] vs. [reference group]. For continuous variables, estimates represent the change per unit increase in the variable.