Do blue light glasses actually work?

• Blue light is a normal part of everyday life, mostly coming from natural sunlight rather than screens.
• The best available scientific evidence does not support blue light filtering lenses to alleviate eye fatigue or discomfort, or to improve sleep quality.
• The amount of light from digital devices (including blue light) is not hazardous, and research does not indicate that blue light filtering glasses provide any additional protection to the macula.

The sun emits a vast amount of energy (electromagnetic radiation), and the light that the human eye can see is called the visible light spectrum, which ranges approximately between 400–760 nm wavelengths.1 Our eyes contain cells that can interpret the different colours within the visible light spectrum – red, orange, yellow, green, blue, and violet. Blue light (400–500 nm) falls within the shorter-wavelength, higher-energy end of the visible light spectrum.

The largest source of blue light exposure is from natural sunlight, which far exceeds that of indoor lighting. Even on a cloudy day, the brightness of outdoor light can be 15–130 times greater than indoor environments.2 Digital devices such as smartphones, tablets, and computers also emit blue light because they often use light-emitting diodes (LEDs) to backlight their displays. 

Considering the widespread use of technology, the prolonged periods of time spent viewing digital devices, often at close range and at night time, concerns have been raised about the potential harm associated with blue light exposure.

‘Blue light glasses’, ‘blue light filtering lenses’, and ‘blue blocking glasses’ refer to glasses containing lenses that are designed to reduce the amount of UV radiation and visible blue light that reaches the eyes.3 Standard glasses lenses are normally not designed to filter blue light.

Blue light filtering can be achieved in one of two main ways. Some lenses absorb a portion of blue light using a coloured tint (e.g. yellow or amber) built into the lens material.4 Others may reflect blue light away from the eyes using special coatings that specifically filter out the blue spectrum of light. Not all blue light lenses filter the same amount of blue light: as studies have shown, this can vary from 6–43%.5

Nowadays, blue blocking lenses have become increasingly popular, particularly among people who spend long hours viewing screens and other types of close work. They are often claimed to reduce eye fatigue, improve sleep quality, and potentially protect eye health (at the retina) following the use of digital devices.6

Symptoms of eye strain, such as sore eyes, eye fatigue, headaches, blurred vision, and dry eyes, can affect up to 90% of people who use computers – and this is commonly known as Computer Vision Syndrome (CVS).7 

While the symptoms of CVS are real, they are not necessarily caused by blue light alone. Studies have consistently found no difference between blue light filtering lenses and non-blue light filtering lenses in terms of reducing eye fatigue.3

Computer work is visually demanding because it requires focusing on small targets, maintaining clear and single vision, and constant eye scanning across a display. Viewing screens for extended periods of time, using smaller screens (e.g. laptops or smartphones), or viewing at closer distances, can worsen these demands. Therefore, uncorrected vision, eye coordination disorders, and dry eyes are the most common culprits of these computer-related vision discomfort.7 

Humans are diurnal species, which means that we are active during the day, and sleep at night. In the right amounts and at the right times, blue light plays an important role in regulating the body’s internal clock, also known as the circadian rhythm.

During the day, blue light exposure (i.e. from natural sunlight) is beneficial by limiting the production of the sleep hormone melatonin – and supporting alertness, mood, and productivity.8 At night, the absence of blue light helps melatonin levels rise and encourages the onset of sleep. 

Blue light exposure may be a problem in the evening or at night. There is growing evidence that blue light from digital devices can interfere with sleep when used at night, particularly in the hours before sleep.9 However, based on the current studies, the effects of blue light filtering glasses for sleep quality remains very uncertain.3 

There are some concerns that blue light may cause long-term eye damage, especially at the macula, as it is the central portion of the retina (at the back of the eye) responsible for detailed vision. However, there is currently no evidence to support the use of blue light filtering lenses for providing protection to the macula.3 

Overall, the light emitted from digital device screens is not harmful, because the front of the eye can absorb the majority of blue light before it reaches the retina. The lens within the eye plays a significant role in absorbing blue light, acting as a natural filter.10 As we age, the lens becomes less transparent and more yellow in colour, boosting its ability to absorb blue light – to the point that by the time people reach 50 years of age, only 20% of blue light reaches the retina.11