Myopia, or near-sightedness, is the most common refractive vision disorder and predisposes the eye to many blinding conditions in adulthood. According to a new paper published in the journal Sleep, people with myopia have more delayed circadian rhythms and lower production of melatonin, a hormone secreted in the brain and responsible for regulating sleep at night, compared to people with normal vision. “Our study adds to the growing evidence of the potential association between disruption of the circadian rhythm and the development of myopia,” said Dr. Ranjay Chakraborty, an optometrist at the College of Nursing and Health Sciences and the Caring Futures Institute at Flinders University. “Disruptions in circadian rhythms and sleep due to the advent of artificial light and the use of light-emitting electronic devices for reading and entertainment have become a recognized health concern in several fields, but its impact on eye health has not been studied extensively.” “These findings provide important evidence that optimal sleep and circadian rhythms are not only essential for general health, but also for good vision.” In the study, Dr. Chakraborty and colleagues recruited 18 young myopic participants and 14 participants with normal sight. Circadian timing was assessed using salivary dim light melatonin onset, collected half-hourly for 7 h, beginning 5 h before and finishing 2 h after individual average sleep onset in a sleep laboratory. Total melatonin production was assessed from urine samples collected from 06:00 pm and until wake-up time the following morning. Objective measures of sleep timing were acquired a week prior to the sleep laboratory visit using an actigraphy device. “The young adults with myopia had significantly delayed circadian rhythms and lower outputs of melatonin compared to normal sighted participants,” Dr. Chakraborty said. Myopia generally occurs in children around the stage of puberty but can also appear at any age in early childhood. A lot of digital devices emit blue light, which can suppress the production of melatonin and cause delay in circadian rhythms at night, resulting in delayed and poor sleep. “Children’s sleeping habits and exposure to screen time must be re-evaluated to reduce the chances of myopia progressing in young people,” Dr. Chakraborty said. “Adequate sleep is critical for learning, memory, sustained attention, academic performance at school, and general wellbeing of children during the early development.” Source
