Blue Light

How does blue light affect children’s eyes?

Blue light disrupts children’s sleep patterns, especially when they are exposed to it before going to sleep at night — that is, when they use a phone, tablet or computer or watch TV just before bedtime. Not getting enough sleep affects children’s growth, attention and success at school.

What problems can be seen in children constantly exposed to blue light?

The clear layer (cornea) and lens of a child’s eye let through more light than an adult’s. Children under the age of two should not be allowed to use digital screens. In older children, eye strain, difficulty focusing, dry eye and headache caused by looking at digital screens too much can affect learning and productivity.

Are there studies on the harmful effects of blue light? If so, what did they find?

During the day, blue light has a positive effect on our attention, reaction speed and mood, but exposure at night disrupts our biological clock. It has been suggested that this may lead to cancer, diabetes, heart disease and obesity.

When and how should we protect ourselves from blue light?

We should take measures against blue light at night. We should stop looking at electronic devices that emit blue light 2–3 hours before going to sleep, or use glasses that filter blue light. The colour we choose for a night light should also be red.

What is the circadian rhythm? Why is it important, and how does blue light affect it?

The body’s internal rhythm covering 24 hours is called the circadian rhythm. The main environmental factor affecting it is light. Sleep at night is brought about by melatonin released from the brain, and the signal that tells the brain whether or not to release melatonin is melanopsin, released by light-sensitive cells in the eye. In other words, when light decreases, the eye sends the brain a signal to sleep. Blue light is the colour of light that suppresses melatonin the most. If we are exposed to blue light at night, we cannot sleep and our sleep pattern is disrupted.

Does blue light have harmful effects on the retina (the nerve layer of the eye)?

Experimental studies have shown that blue light causes damage to the retina. There are also studies suggesting that the blue light we are exposed to over our lifetime may play a role in age-related macular degeneration, which causes loss of vision. However, many factors are involved in the development of age-related macular degeneration, and the effect of blue light alone has not yet been fully proven.

Advice for people who use computers, phones and tablets constantly

Keep the screen 35–40 cm away from you.

At least 3 times an hour, look up from the screen and into the distance.

If you develop signs of dryness such as redness or stinging, use artificial tear drops.

Stop using screens 2–3 hours before going to sleep, or wear glasses that block blue light.

Have an eye examination once a year.

Are there special products we can use to protect ourselves from blue light?

To protect ourselves from blue light, we can use spectacle lenses that block it. Besides protecting against blue light, these lenses reduce glare and give more comfortable vision, and they let us see colours more naturally.

Who chooses them most?

These lenses should be chosen by people who spend long hours at a computer. People who use their mobile phones a lot or watch television for long hours should also use lenses that block blue light.