At the last follow-up, the respective mean myopia progression values for all children, boys, and girls were –1.89 ± 1.28 D, –1.71 ± 1.25 D, and –2.10 ± 1.30 D; boys demonstrated a significantly smaller myopic progression than girls (
P < 0.001). The respective mean axial elongation values for all children, boys, and girls were 1.22 ± 0.57 mm, 1.16 ± 0.56 mm, and 1.29 ± 0.58 mm, respectively; boys also demonstrated a significantly smaller axial elongation than girls (
P < 0.001). The myopia progression and axial elongation in four years according to sleep duration are shown in
Table 2. Sleep duration was not significantly associated with myopia progression and axial elongation for all children (ANOVA;
P = 0.70;
P = 0.114). When the analysis was split by sex, there was a significantly decreasing myopia progression and axial elongation with increasing sleep duration in girls (ANOVA,
P = 0.013;
P = 0.002) but not in boys (ANOVA,
P = 0.24;
P = 0.74). Compared with children in the middle sleep duration tertile, girls in the highest sleep duration tertile had myopia progression of 0.31 D less (ANOVA,
P = 0.040, post hoc Scheffé test) and axial elongation 0.15 mm shorter (ANOVA,
P = 0.014, post hoc Scheffé test). However, no significant difference between the highest sleep duration tertiles and low sleep duration tertiles was found in myopia progression and axial elongation (
P = 0.07;
P = 0.11). In addition, there was no significant difference between bedtime levels with myopia progression and axial elongation (ANOVA,
P = 0.66;
P = 0.88;
Table 3).