Is myopia progression related to sleep duration?

Paper title: Sleep Duration, Bedtime, and Myopia Progression in a 4-Year Follow-up of Chinese Children: The Anyang Childhood Eye Study

Authors: Wei, Shi-Fei;¹ Li, Shi-Ming;¹ Liu, Luoru;² Li, he;² Kang, Meng-Tian;¹ Sun, Yun-Yun;¹ Wang, Yi-Peng;² Yang, Xiao-Yuan;³ Wang, Ningli¹

1. Beijing Institute of Ophthalmology, Beijing Tongren Eye Centre, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, China
2. Anyang Eye Hospital, Henan Province, China
3. Department of Ophthalmology, Zhengzhou Second Hospital, Henan Province, China

Date: Mar 2020

Reference: Wei SF, Li SM, Liu L, Li H, Kang MT, Sun YY, Wang YP, Yang XY, Wang N. Sleep Duration, Bedtime, and Myopia Progression in a 4-Year Follow-up of Chinese Children: The Anyang Childhood Eye Study. Invest Ophthalmol Vis Sci. 2020 Mar 9;61(3):37.

[Link to open access paper]

With a global increase of myopia prevalence, many potential risk factors such as time spent outdoors and educational pressure have been explored. Currently, there are mixed results for evidence of a relationship between length of sleep and myopia in children.¹

The Anyang Childhood Eye Study assessed myopic progression and axial length elongation of schoolchildren in relation to their bedtime and sleep patterns over a 4yr period.

Over the study period, an overall myopia progression of -1.89D and axial length growth of 1.22mm was found.  When sleep duration was considered, girls in the highest sleep duration group who slept for over 10hrs showed 0.31D less progression and reduced axial length growth of 0.15mm, compared to girls in the middle duration group who slept for up to 10hrs.  This advantage was not seen when comparing to the girls in the lowest sleep duration group and also not seen when the boys sleep duration times were compared.  

While this study found no significant association of sleep duration and bedtime on myopia progression and axial length growth, when the sexes were compared it was found that girls showed a general increase in progression rate compared to boys (-2.10D vs. -1.71D) as well as longer axial lengths (1.29mm vs. 1.16mm).  Axial elongation was found to decrease by a rate of 0.086mm per extra hour of sleep for the girls only, although this was considered to be a clinically insignificant value. 

We cannot be sure at this stage which has more influence on myopia development or progression; prolonged close work, reading or screen use late into the evening which may mean a later bedtime, or the later bedtime itself.  It is possible that either, or both, are responsible.  As such, eyecare practitioners can provide lifestyle advice even with this uncertainty.

Although this study found no significant association between sleep duration and myopia progression, circadian rhythms and eye development are widely accepted to be linked.¹ Further research into the pathways responsible for myopia development could reveal the role sleep plays in this process and if age, sex or ethnicity make a difference to its influence.

The influence of sleep patterns and sleep quality on myopia development, progression and axial length elongation also requires further study.  It could also establish if faster myopia progression in girls is associated with their earlier onset of puberty.

Title: Sleep Duration, Bedtime, and Myopia Progression in a 4-Year Follow-up of Chinese Children: The Anyang Childhood Eye Study

Authors: Shi-Fei Wei, Shi-Ming Li, Luoru Liu, He Li, Meng-Tian Kang, Yun-Yun Sun, Yi-Peng Wang, Xiao-Yuan Yang, Wang, Ningli Wang

Purpose: To investigate the relationship between sleep duration and bedtime with myopia progression and axial elongation during a 4-year follow-up in primary school children.

Methods: This study included 1887 children (aged 7.09 ± 0.41 years) who had cycloplegic refractions data at baseline and a fourth visit and 2209 children (aged 7.10 ± 0.41 years) for axial length. All children underwent comprehensive ophthalmologic examinations, including cycloplegic refraction and ocular biometry, and standardized questionnaires, including average night-time sleep duration (h/d) and bedtime (time to bed). Myopia was defined as spherical equivalent < -0.5 diopters.

Results: At the last follow-up, the mean myopia progression and axial elongation for all children were -1.89 ± 1.28 diopters and 1.22 ± 0.57 mm. After stratifying the sleep duration into tertile groups, myopia progression and axial elongation were slower in children with highest sleep duration tertile (P = 0.04 and P =0.014) in girls but not in boys, compared with the middle sleep duration tertile. However, after adjusting for potential confounders, no significant association was found for sleep duration with myopia progression and axial elongation for the children (P = 0.255 and P = 0.068), and the association with axial elongation was only of borderline significance in girls (P = 0.045). The bedtime was not associated with myopia progression and axial elongation in the regression analyses (P = 0.538; P = 0.801).

Conclusions: These results show that there was no significant association between sleep duration and bedtime with myopia progression and axial elongation among children. The findings in girls might be related to the earlier onset of puberty.

[Link to open access paper]