A French health authority has warned that the blue light used in LED lights can damage the retina of the eye and disturb natural sleep patterns, known as the circadian rhythm. So, what’s the evidence and what potential harm is being done?

Are LED Lights Damaging Your Eyes And Disturbing Sleep?

Harmful Effects Of Blue Light

Blue light photoreceptors in the retina of the eye communicate directly with the brain circadian clock. Exposure to blue light, particularly in the evenings is known to negatively affect sleep by inhibiting the synthesis of the sleep-inducing hormone, melatonin. This is also likely to be due to the effect blue light has on increasing alertness, similar to that of the stimulant caffeine found in the popular coffee drink.

By disrupting the circadian rhythm, sleep duration and quality tends to be reduced. This can lead to increased recovery time from exercise and everyday stress, increased hunger, an increased likelihood to get irritable during the day, higher susceptibility to disease and fatigue, all of which can lead to chronic stress over a prolonged period of time.

The French Agency for Food, Environmental and Occupational Health & Safety, known as ANSES has found phototoxic effects of short-term exposure to high-intensity blue light as well as a risk of age-related macular degeneration that comes with chronic exposure to lower intensity sources. Age-related macular degeneration is a major cause of vision loss in people over 50 and is caused by damage to the macula, a small spot near the centre of the retina which is required for good vision.

ANSES differentiates different types of blue light. ‘Warm white’ light from LED light has weak phototoxicity risks, similar to that of traditional lighting in lightbulbs whereas other LED light sources such as those used in car headlights, newer flashlights and certain toys emit a whiter and ‘colder’ blue light which is said to be more harmful.

An American study has described how blue light has become ‘increasingly prominent’ in the modern world with many scientists convinced that exposure of LED light in the range of 470 – 480 nanometres for a short duration (days to weeks) will not significantly increase the risk of eye disease, but long-term exposure (months to years) may significantly increase the risk of eye disease. However, more studies are needed to verify the risk of long-term exposure to blue light.

Use Of LED Lights And Blue Light

Blue light has always been around. It’s emitted from the Sun as higher energy wavelengths in the visible light electromagnetic spectrum. Traditional light bulbs emit blue light although it’s not as much as that of LED lights.

LED lights are being used more and more in housing since they are more economical and use significantly less electricity per lumen than traditional light bulbs.

Preventative Measures

Some ways you can reduce exposure to blue light include using a ‘night mode’ on electronic devices such as your phone, tablet or computer. This tends to give the screens a yellow ‘tinge’ as they filter out most of the blue light being received by the photoreceptors in your retina. You can also dim the brightness of electronic devices during the evening to reduce the intensity of any blue light emitted. It may also be a good idea to slowly dim the lights in the evening and use less light in order to live and sleep more naturally since we wouldn’t have any of these problems if we didn’t have lights and had the light of the day and night cycle dictating when we slept and rose.

ANSES has said that protection from the harmful effects blue light which is offered by ‘anti-blue light’ screens, filters and sunglasses varies and their ability to preserve sleep patterns and prevent disruption of circadian rhythms is not yet proven. This is backed up by an unrelated review of scientific studies in 2017 which suggests sunglasses and filters may not protect us and lack high-quality evidence to support their use. However, sunglasses may have an effect since they block out ultraviolet light and those with a ‘yellow tint’ will reduce the amount of blue light reaching the retina.

Even if the evidence is limited, I can’t see that it would hurt to try night filters so here’s what I would try and do:

  • Use a night filter on electronic devices from 8 pm onwards.
  • Become less reliant on lights after anywhere between 7 pm and 8 pm (adjust to your schedule).
  • Wear sunglasses at night (I’m only joking although you can).
  • Try to dim the lights at night.
  • If you need the toilet at night, try and go without turning on the lights.

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