Visible light, essential for sight, isn't inherently harmful in typical amounts. However, excessive exposure, especially to high irradiance or specific wavelengths like blue light, can cause damage.
The Impact of Visible Light Intensity
The key factor determining visible light's harmfulness is its intensity. Low levels of visible light are harmless and necessary for vision and our biological functions, including regulating our body clock. [Light is not only used for sight but also has an influence on endogenous messenger substances and sets the "body clock". If the irradiance exceeds certain levels, light can also be harmful – especially to the eyes.](Reference 1) But high irradiance levels can cause thermal damage – essentially, burning – to the eyes and skin. [Although thermal damage – that is, damage due to heating – is possible, this only occurs at higher irradiances.](Reference from BfS link)
Harmful Wavelengths and Long-Term Effects
While all visible light can be harmful at very high intensities, certain wavelengths pose greater risks. [These data suggest that high levels of exposure to blue or visible light may cause ocular damage, especially later in life.](Reference from JAMA Ophthalmology link) Blue light, for example, penetrates deeper into the eye, potentially contributing to age-related macular degeneration and other eye problems. [Visible light can penetrate the full thickness of the skin and induce pigmentation and erythema.] (Reference from PMC article) Furthermore, visible light can indirectly damage DNA through the generation of reactive oxygen species. [It has also been shown that visible light can induce indirect DNA damage through the generation of reactive oxygen species.](Reference from Pubmed link)
Examples of Harmful Effects:
- Eye damage: High-intensity visible light can burn the retina, causing temporary or permanent vision loss. Prolonged exposure to high levels of blue light may contribute to age-related macular degeneration.
- Skin damage: While less pronounced than UV damage, intense visible light can contribute to skin aging and potentially increase the risk of skin cancer. Visible light can cause erythema (redness) and increased pigmentation.
- Sleep disruption: Exposure to blue light, especially in the evening, can interfere with melatonin production, disrupting sleep patterns.
Practical Insights:
- Moderate sunlight exposure is beneficial for Vitamin D production but prolonged exposure necessitates eye protection.
- Using blue light filters on electronic devices can reduce eye strain and improve sleep quality.
- High-intensity light sources, like lasers, require specialized safety measures.
