Blue Light and Digital Insomnia
Blue-light blocking lenses are currently being marketed as the solution to digital eye strain, macular degeneration, and sleep cycles. There are conflicting claims to the benefits of these lenses and the dangers that blue light may impose on our eyes. It's hard to know what's true and what advice we should take with a grain of salt. Here's a summary of information and real advice provided by The Royal Australian and New Zealand College of Ophthalmologists (RANZCO). (1)
Short-wavelength blue light falls within 400-500nm range of the visible spectrum. Shorter wavelengths of the electromagnetic spectrum emit more energy and within 100-400nm are considered ultraviolet (UV). Intense or long-term UV radiation including that from the sun is known to cause damage to the retina and ocular tissue. The cornea and lens in the eye absorbs most natural UV light as a protective mechanism however, a small amount is transmitted with the visible spectrum. In the retina we have macula pigments called zeaxanthin, lutein, and meso-zeaxanthin which absorb 40% of high energy (short wavelength) light that gets through to the retina. Natural source of blue light is from the sun and artificial blue light comes from devices. (1)
There is no evidence that normal environmental exposure to blue light is detrimental to eyesight. Animal studies using unrealistic intensities and duration are not a fair comparison to our natural viewing environment. The amount of radiation from digital screens such as computers, mobile phones, and television has never been found to cause any eye disease. Studies have found no measurable amount of UVA or UVB radiation from computer monitors. Sitting close to UV on the electromagnetic spectrum, blue light is often marketed as dangerous to eye health. Blue light during daylight hours is actually beneficial and is known to boost attention, reaction times, and mood to keep us alert and awake for daytime activities. At night time blue light can be disruptive to mood and circadian rhythm (biological clock). The cells sensitive to lower wavelength blue light in the retina help to regulate the circadian rhythm and studies have shown that night time exposure of blue light to these photoreceptors, the ipRGCs can disrupt the sleep cycle keeping you up at night. (1)
Digital eye strain is any eye strain experienced from using digital devices such as your phone, computer, or television. It is caused by prolonged use of these devices or as a result of reduced blink rate from long periods of concentration. Inefficient ocular accommodation or ability to change focus can also cause digital eye strain. Numerous studies have investigated but found little to no evidence to suggest that blue light blocking lenses alleviate eye strain when compared with plain lenses. (1, 3)
In summary blue light from screens and our natural environment are not detrimental to your eyesight or ocular health but it can disrupt your sleep cycle at night time. The general statement regarding blue light blocking lenses from RANZCO is that, ""No evidence exists to suggest that normal environmental exposure to blue light, including those from digital screen technology, causes damage to eyesight. Filtering out the blue light from screens is not necessary in general use." To prevent digital eye strain it is recommended to take regular breaks, occasionally look at distant objects, and make sure you are using suitable prescription glasses if required. It is also advisable to avoid screen use a couple hours before bedtime. (1, 2). Those who do use digital devices at night may find the benefit of blue blocking lenses however, especially if they find themselves struggling to sleep at night.