O083 Myopic, or Short-sighted, Children show Delayed Melatonin Circadian Timing, Lower Melatonin Output and Sleep Disruptions

INTRODUCTION: Recent studies have reported poor and reduced sleep in myopic, or short-sighted, individuals. Here, we investigated differences in melatonin secretion timing and output and actigraphy-derived sleep in myopic and non-myopic (or emmetropic) children, aged 8-15 years. METHODS: 26 myopes [refractive error (mean ± standard error mean) -2.06 ± 0.23 dioptres] and 19 emmetropes (-0.06 ± 0.04 dioptres), aged 11.74 ± 2.31 years were recruited. Melatonin timing was assessed using salivary dim light melatonin onset (DLMO), collected half-hourly for 7 hours in a sleep laboratory, beginning 5 hours before and finishing 2 hours after habitual bedtime for the past week. Total melatonin production was assessed via aMT6s levels from urine voids collected from 05:30 pm and until 08:00 am the following morning. Actigraphy-derived sleep was acquired for one week prior to the sleep laboratory visit. RESULTS: Myopic children (21:07 ± 0.2 hrs) had a DLMO time 1.1 hrs later compared to emmetropes (19:59 ± 0.2 hrs), p=0.002. aMT6s melatonin levels were significantly lower among myopes (18.70 ± 2.38) than emmetropes (32.35 ± 6.93, p=0.001). Myopes also exhibited significantly delayed sleep onset (21:42 ± 0.2 vs 23:00 ± 0.2 hrs), delayed wake-up time (06:38 ± 0.2 vs 07:29 ± 0.1 hrs), shorter sleep duration (8.1 ± 0.2 vs 7.6 ± 0.1 hrs), and more evening-type diurnal preference than emmetropes (all p<0.05). DISCUSSION: These findings suggest a potential association between circadian rhythm dysfunction and myopia in children, supporting towards a shared mechanism of myopia and delayed sleep-wake phased disorder development during adolescence.