Several studies have shown that outdoor activities are effective in preventing the onset of myopia.

Let's go outside and soak up the sunlight.
It is said that the longer you spend outdoors, the lower your risk of developing myopia, and the ideal is two hours a day.
These two hours don't have to be consecutive. Aim for a total of two hours throughout the day, including commuting time, physical education classes, etc.

It is said that as long as it is outdoors, shade from a building or tree, or even on a cloudy day, is fine, rather than direct sunlight.
Furthermore, there are reports suggesting that certain wavelengths in sunlight are associated with inhibiting the progression of myopia.

A study analyzed the relationship between children's outdoor activity time and the incidence of myopia, separating the analysis by whether or not their parents were myopic. Even if neither parent was myopic, short outdoor activity times increased the likelihood of developing myopia.

The closer you are to the viewing distance, such as when looking at notebooks, tablets, smartphones, or portable game consoles, the more your eyes need to converge and adjust their focus, increasing the risk of eye strain and nearsightedness.

It would be good to be aware of viewing distance using everyday objects.

For example, the longer side of an A4 sheet of paper is 29.7 cm, so you can measure the distance by checking whether an A4 sheet of paper fits between your eyes and the object you are looking at. If you measure the length of your palm or arm beforehand, you can use that as a guideline for 30 cm even when you are out and about. Also, to maintain a viewing distance of 30 cm, make it a habit to maintain good posture when looking at things up close. Be careful not to tilt your head and bring one eye extremely close to the desk, as this can worsen myopia in the eye that is closer. Be mindful of this when you are sitting at a study desk, for example.

Prolonged periods of close-up work, such as using notebooks, tablets, or smartphones, can strain your eyes.

To rest your eyes, take a break every 30 minutes by looking at something far away for at least 20 seconds.
* The American Academy of Ophthalmology recommends the "20-20-20 rule."
The instructions state that if you look at a digital device screen for 20 minutes continuously, you should look at something 20 feet (approximately 6 meters) away for at least 20 seconds.

Studies have shown that children with high myopia have lower sleep quality compared to children without it.

To sleep well, it's important to regulate your sleep-wake cycle by getting sunlight during the day and dimming the lights at night.
Furthermore, the blue light emitted from the screens of computers, smartphones, and game consoles is said to have a "waking-up" effect on the body. Try to stop using these devices at least one hour before going to bed.

A study analyzing the relationship between sleep and myopia was conducted on patients who visited six ophthalmology medical institutions in Japan, including Keio University Hospital. The results showed that children with high myopia (ages 10-19) went to bed later and slept for shorter periods compared to children without myopia.

While myopia often develops in the third or fourth grade of elementary school, it is becoming more common at younger ages these days. In some cases, it can develop as early as before the age of six.
Since nearsightedness tends to progress with age, it is recommended to start preventative measures early.

*This varies depending on genetics and lifestyle. Some people develop myopia in adulthood, and in some cases, the progression of myopia may not stop.