During the past decade, eye health professionals have become increasingly concerned about a startling rise in both the rate and severity of myopia. Commonly referred to as nearsightedness, myopia has been increasing on a global scale, and quite dramatically in many world regions. Children in urban Asian areas, for example, are experiencing skyrocketing rates, with 84 to 97 percent of older teens and young adults having myopia in some regions. Recent research out of Flinders University in Australia has offered fascinating new insights on this increase, with researchers finding disruptions in circadian rhythm linked to myopia.
Disruptions in Circadian Rhythm Linked to Myopia
Flinders University researchers conducted a study that compared circadian rhythm timing and melatonin levels between a group of people with myopia and a group with normal vision. Melatonin is a hormone associated with the regulation of the circadian rhythm and sleep/wake timing. Production of this hormone starts after dark and its excretion is typically greatest from 2:00 a.m. to 4:00 a.m. Those with myopia were found to have lower melatonin production levels and were more likely to have delayed circadian rhythms, both of which are associated with poor quality sleep and also linked to a greater risk of developing myopia.
Interestingly, a 2017 study found those with myopia had higher melatonin levels than did people with normal vision. This University of Ulster in Coleraine, UK, study tested their participants during September and October, then again about 18 months later, during March and April, allowing them to investigate the potential for seasonal changes. The blood draws used to check melatonin levels were taken at 8:30 a.m. and 10:00 a.m.
The higher melatonin levels that were detected in the 2017 study are not necessarily as contradictory as may seem at first glance. After all, with melatonin typically peaking between 2:00 a.m. to 4:00 a.m., those higher levels found in nearsighted people in blood drawn at 8:30 a.m. and 10:00 a.m. can actually be indicative of circadian rhythm disruption or a delayed circadian rhythm.
In looking at potential causes for the global increase of myopia, the concept of light – natural, outdoor light – has come up again and again. Natural light has been shown to be essential to eye health and to have a role in the prevention of myopia. However, in our modern way of life, exposure to natural light has been greatly reduced.
Urban living often entails inside work, rather than the outside work that is integral to more agrarian living. Children spend less time playing outdoors than previous generations did and more time inside with screens and electronic devices, leading eye health professionals to specifically recommend children spend more time playing outside to help develop and protect their vision.
This recent research linking circadian rhythm disruption and myopia adds an additional element to the connections between light and myopia by illustrating how tightly linked the circadian rhythm is to light. Light is among the most powerful of the environmental cues that the circadian rhythm relies upon. Decreased exposure to natural light, especially during morning hours, and an increase in the use of artificial light, particularly in the evening, can be disruptive to the circadian rhythm and have a negative impact on melatonin production.
Maintaining a Healthy Circadian Rhythm
Your circadian rhythm has evolved through countless generations to the approximately 24-hour cycle of day and night. It impacts your health and well-being in numerous ways. Chronic disruption of the circadian rhythm is linked to a higher risk of a wide variety of diseases and health conditions. A healthy circadian rhythm is an essential part of your short-term and long-term physical health, mental well-being and cognitive functioning.
While the most important means of obtaining and maintaining a healthy circadian rhythm are fairly simple, it can be a challenge to achieve in the context of modern, urban living. So, perhaps the first steps are to understand just how fundamental this rhythm is to your health and to make better health a priority, including prioritizing sufficient sleep in your daily life. Set regular sleeping and waking times, allowing for enough sleep each day. Try hard to get up and go to bed at the same times every day.
Increase your natural light exposure. Your circadian rhythm needs these cues. Morning light is important, but so too is getting a bit of natural light exposure during the sunset. Limit exposure to bright lights in the evening, especially in the two hours before bedtime. It is best to decrease screen and electronic use during that period of time as well.
Getting enough physical activity is essential for health and it is also important for your circadian rhythm. Try to get your physical activity in the morning sunlight. Don’t workout in the evening, because that can contribute to circadian rhythm disruption. Set a regular schedule for meals, avoiding heavy evening meals. Decrease caffeine use in the afternoons and eliminate it from your evenings.
Points to Keep in Mind
Developing better habits takes time. Making lifestyle changes to allow for the sufficient sleep, optimal day and evening light exposure and regular meal times you need for a healthy circadian rhythm can be a challenge. Make the changes you can now and continue to work towards improvement, choice by choice and day by day.