Myopia, or near-sightedness, is associated with delayed melatonin circadian timing and lower melatonin output in young adult humans

Ranjay Chakraborty, Gorica Micic, Lisa Thorley , Taylah R Nissen , Nicole Lovato, Michael J. Collins , Leon Lack

Research output: Contribution to journalArticlepeer-review

Abstract

Study objectives Myopia, or near-sightedness, is the most common refractive vision disorder and predisposes the eye to many blinding conditions in adulthood. Recent research has suggested that myopia is associated with increased endogenous melatonin production. Here we investigated the differences in melatonin circadian timing and output in young adult myopes and non-myopes (or emmetropes) as a pathogenesis for myopia. Methods Eighteen myopic (refractive error [mean ± standard deviation] -4.89 ± 2.16 dioptres) and 14 emmetropic participants (-0.09 ± 0.13 dioptres), aged 22.06 ± 2.35 years were recruited. Circadian timing was assessed using salivary dim light melatonin onset, collected half-hourly for 7 hours, beginning 5 hours before and finishing 2 hours after individual average sleep onset in a sleep laboratory. Total melatonin production was assessed via aMT6s levels from urine voids collected from 6 pm and until wake-up time the following morning. Objective measures of sleep timing were acquired for a week prior to the sleep laboratory visit using an actigraphy device. Results Myopes (22:19 ± 1.8 hrs) exhibited a dim light melatonin onset phase-delay of 1 hr 12 min compared to emmetropes (21:07 ± 1.4 hrs), p=0.026, d = 0.73. Urinary aMT6s melatonin levels were significantly lower among myopes (29.17 ± 18.67) than emmetropes (42.51 ± 23.97, p=0.04, d = 0.63). Myopes also had a significant delay in sleep onset, greater sleep onset latency, shorter sleep duration and more evening-type diurnal preference than emmetropes (all p<0.05). Conclusions These findings suggest a potential association between circadian rhythms and myopia in humans.
Original languageEnglish
JournalSLEEP
DOIs
Publication statusE-pub ahead of print - 8 Oct 2020

Keywords

  • melatonin
  • circadian rhythms
  • myopia
  • sleep
  • refractive error
  • axial eye length

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