Myopia, or nearsightedness, is the most common refractive visual disorder and predisposes the eye to many adult states of blindness. According to a new article published in the magazine Sleep, People with myopia have a delayed circadian rhythm and lower production of melatonin, a hormone secreted in the brain responsible for regulating night sleep, compared to people with normal vision.
“Our study is adding to the growing evidence of the possible link between a disruption of the circadian rhythm and the development of myopia,” said Dr. Ranjay Chakraborty, optometrist at the College of Nursing and Health Sciences and the Caring Futures Institute at Flinders University.
“Disturbances in circadian rhythm 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 problem in several areas, but their effects on eye health have not been fully studied.”
“These results provide important evidence that optimal sleep and circadian rhythms are essential not only for general health, but also for good eyesight.”
In the study, Dr. Chakraborty and colleagues 18 young myopic participants and 14 participants with normal eyesight.
Circadian timing was determined from melatonin onset in low saliva light, collected every half hour for 7 hours, starting 5 hours before and 2 hours after the individual’s average asleep in a sleep laboratory.
Total melatonin production was determined from urine samples collected from 6:00 p.m. until waking up the next morning.
Objective measurements of sleep timing were recorded with an actigraphy device one week before the sleep laboratory visit.
“The young adults with myopia had a significantly delayed circadian rhythm and lower melatonin secretion compared to normal-sighted participants,” said Dr. Chakraborty.
Myopia generally occurs in children during puberty, but can also occur at any age in early childhood.
Many digital devices emit blue light, which can suppress melatonin production and delay the circadian rhythm at night, resulting in delayed and poor sleep.
“Children’s sleeping habits and exposure to screen time need to be reassessed to reduce the likelihood of progressive myopia in young people,” said Dr. Chakraborty.
“Adequate sleep is critical to learning, memory, sustained attention, academic performance, and general well-being of children during early development.”
Ranjay Chakraborty et al. 2021. Myopia, or nearsightedness, has been linked to delayed circadian melatonin timing and decreased melatonin production in young adult people. Sleep 44 (3): zsaa208; doi: 10.1093 / sleep / zsaa208