Blue light and its effects: practical recommendations

Published on 18 December 2024 · Updated on 12 June 2025

Despite widespread media reports suggesting that blue light could harm the eyes, there are no rigorous scientific studies confirming significant visual damage. Studies of this kind lack conclusive evidence, so the Sociedad Española de Oftalmología (SEO) has made its position clear on the effects of blue light emitted by electronic devices: blue light is not harmful to eye health unless proved otherwise.

Myths and facts

As we know, spending hours in front of computer, mobile phone or tablet screens exposes us to blue light, but this exposure is minimal and, as we have seen, does not pose a serious eye risk. In fact, the amount of blue light these devices emit is considerably lower than the natural blue light we are exposed to from the sun every day.

The only documented health effect of blue light is its influence on the circadian rhythm. During the day, this light helps keep us awake and alert; however, excessive exposure at night, particularly before bedtime, can make it harder to fall asleep. Reducing screen time in the hours before bed or activating “night mode” on devices to reduce blue light intensity is therefore recommended.

Prolonged screen use can also cause digital eye strain, not because of blue light itself, but because of the continuous effort of focusing and the fact that we blink less in front of screens. This can cause dryness and tired eyes. To prevent these symptoms, it is recommended to follow the 20-20-20 rule: every 20 minutes, look at an object about 6 metres (20 feet) away for 20 seconds. Artificial tears can also help relieve symptoms.

Are blue-light-filtering glasses necessary?

As there is no scientific evidence that blue light from screens causes eye damage, the SEO does not recommend special blue-light-filtering glasses, since their effectiveness is questionable. Rather than protection against blue light, preventing eye problems involves good screen-use habits, taking breaks and, if necessary, consulting an ophthalmologist for personalised guidance. Please contact us: at Clínica Castellote, we can answer this and other questions about eye health and electronic device use.

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