Abstract
Purpose :
Previous studies, primarily using questionnaires, suggest a possible relationship between sleep and myopia. Sleep is known to be influenced by light exposure and physical activity. This study aimed to examine the influence of day of the week, season, time outdoors, and physical activity on objectively measured sleep parameters in non-myopic and myopic children.
Methods :
Objective measures of light exposure, physical activity, and sleep were collected from 91 children aged 10 to 15 years using a wrist-worn actigraph device (Actiwatch 2) over two 14-day measurement periods approximately 6 months apart. Each measurement period was classified as either a longer day/warmer season or a shorter day/cooler season. Noncycloplegic subjective refraction was performed to classify children as non-myopic (spherical equivalent > -0.50 D, n = 55) or myopic (≤ -0.50 D, n = 36). Bed time, wake time, and sleep duration, latency, and efficiency were analysed with respect to season, day of the week (weekday vs weekend), age, gender, and refractive error. Influence of time spent outdoors and physical activity on each sleep parameter was also assessed.
Results :
On weekends, children went to bed later (P < 0.001), had increased sleep duration (P < 0.001), and woke up later (P < 0.001) than on weekdays. During the cooler season, children woke up later (P < 0.001) and slept longer (P = 0.03). Younger children (ages 10-12 years) went to bed earlier (P = 0.005) and woke up earlier (P = 0.01) than older children (ages 13-15 years). Compared to non-myopic children, myopic children had a longer sleep duration on weekends (P = 0.006) and on cooler days (P = 0.01). Additionally, myopic children had a shorter sleep latency on weekends (P = 0.005). Children who were outdoors more tended to have increased sleep duration (β = 0.31, P = 0.03), and children with greater physical activity tended to wake up earlier (β = -0.44, P < 0.001).
Conclusions :
Objectively measured sleep parameters, including bed time, wake time, and sleep duration, were significantly influenced by day of the week, season, and age. Light exposure and activity also demonstrated associations with sleep. Furthermore, myopic children tended to show more variation in sleep duration between days of the week and season than non-myopic children. Further investigation may help to clarify factors contributing to refractive error group differences.
This is a 2020 ARVO Annual Meeting abstract.