Do sleep patterns contribute to myopia in schoolchildren?

Sleep hygiene and duration do not appear to affect the prevalence of myopia among school-aged children, according to a recent Singapore study. Sleep variables are also unrelated to other eye measurements.

“Our study results showed that sleep quality, duration, timing, and the consistency of specific sleep factors at age 8 were not independently associated with myopia, spherical equivalent (SE), or axial length (AL) among school-aged children aged 9 years in Singapore,” the researchers said.

The present cross-sectional study included 572 children (aged 9 years, 49.5 percent boys, 56.1 percent Chinese) who had participated in the Growing Up in Singapore Towards Healthy Outcomes birth cohort from 2009 to 2010. The Children’s Sleep Habits Questionnaire (CSHQ) was used to measure parent-reported sleep quality; other sleep parameters, such as duration and consistency of timing, were also parent-reported.

Most participants (60.3 percent; n=689) had ideal vision, while 427 (37.3 percent) and 28 (2.4 percent) had myopic and hyperopic eyes, respectively. The mean SE was –0.4 D, while average AL was 23.4 mm. [Front Public Health 2022;doi:10.3389/fpubh.2022.828298]

In terms of sleep, parents said that their children slept for a mean of 9.2 hours per day overall; 59.9 percent of children achieved the recommendations for sleep sufficiency. During weekends, children had significantly longer sleep, and there was a higher percentage of children who met sleep sufficiency guidelines. The mean total CSHQ score was 45.8.

Multivariable linear models showed that neither SE nor AL were significantly associated with sleep parameters, such as total CSHQ score (p=0.97 and p=0.37, respectively), sleep duration (p=0.59 and p=0.64, respectively), and sleep sufficiency (<9 vs ≥9 hours per day: p=0.88 and p=0.75, respectively).

Similarly, bedtime, waketime, and duration in bed (total, at night only, and during naps only) were all unrelated to SE and AL.

Myopia, defined as SE ≤ –0.5 D, was also not affected by sleep outcomes, according to multivariable logistic analysis. Total CSHQ score (p=0.38), sleep duration (p=0.16), and sleep sufficiency (<9 vs ≥9 hours per day: p=0.53) did not significantly affect the odds of myopia, nor did duration in bed, bedtime, and waketime.

Moreover, the consistency of sleep duration, duration in bed, bedtime, and waketime were all unrelated with SE, AL, and myopia.

“Overall, the results in this study suggest that sleep factors may not be independently associated with myopia,” the researchers said, pointing out that existing evidence on the matter remained inconsistent. “Together with the null associations in this study, [this] suggests that the evidence supporting specific sleep factors as independent risk factors for myopia remains weak.”

“Although the current findings do not support associations of specific sleep factors with myopia, much larger longitudinal studies may be required to corroborate these results,” they added.