Ask the Pharmacist

Q) I have been hearing about concerns regarding whether the blue light emitted from computers can damage my eyes. Is there any truth to this and if so, should I take one of the supplements on the market to prevent it?

A) Visible light comes in a number of colours depending on the wavelength of the light ray, if you can recall your secondary school physics.

The longest wavelengths produce the colour red and as the wavelengths shorten the colour of the rays change to orange then yellow, green, blue and finally violet. The shorter the wavelength, the greater the amount of energy the ray contains. As such, blue light is one of the highest energy rays the eyes are exposed to.

The display screens of smart phones, tablets, computers and other digital devices emit large amounts of blue light which has produced some degree of concern from scientists and a business opportunity for a number of companies hoping to cash in on this.

However, it should be noted that the amount of blue light produced by all of these devices is only a fraction of the amount we are exposed to from the sun, so it is important to keep the potential harm from these screens in perspective. That acknowledged, given the amount of time people spend in front of screens and the ages at which they start, the topic is still worth investigating.

So, is blue light bad for us and if so, do these products help.

Blue light, like so many things in life can be both good and harmful depending on a number of factors. On the positive side, exposure to blue light has been shown to boost alertness, help memory and cognitive function as well as to elevate mood. In fact, light boxes that are now being used to help combat seasonal affective disorder (perhaps better known as SAD which is a mild to moderate form of depression some feel during the winter months when sunlight is at its lowest/weakest).

These light boxes emit a significant amount of blue light which also plays a very important role in regulating our circadian rhythm, the body’s natural sleep and wakefulness cycle. Exposure to blue light during daylight hours helps maintain a normal circadian rhythm which is important in helping us get a healthy amount of sleep.

On the negative side though, exposure to blue light at night seems to suppress the release of the hormone melatonin which naturally plays a major role in maintaining our circadian rhythm. This may, and the key word here is may, have several negative impacts on our health.

Low melatonin levels, for instance, are associated with sleep deficiencies and these in turn have been linked in some way to an increased risk of acquiring various cancers, diabetes, heart disease and being obese. While any kind of light can suppress sleep, blue at night does so more powerfully. To demonstrate this, in one study Harvard researchers measured the effects of exposure to green light versus blue light for equal amounts of time and at the same relative level of brightness. Recipients of the blue light exposure were found to have their levels of melatonin decreased for twice as long and their circadian rhythms shifted by twice as much when compared to the green light recipients.

As well, while there is no conclusive proof that blue light damages our eye, there are concerns that the additive exposure to it that many of us are now receiving could put more of us at risk for age related macular degeneration, the leading cause of severe loss of vision in people over the age of 60. What is known now is that blue light can cause eye strain (no great surprise for many of us who work on computers all day), blurred vision, fatigue and headaches.

As a result of this, several companies are now producing supplements (Ocu-Blue to name one) that are being promoted to protect eyes from blue light. Most of these contain lutein and zeaxanthin as well as vitamin A along with several other vitamins and minerals. These ingredients are known to support some aspects of eye health and there is some evidence they might reduce eye strain however at this point in time there is no proof they do anything to protect us from blue light and may well not be worth the cost.

As for glasses that advertise they filter out blue light, there was an experiment run at the University of Toronto that showed these glasses had some impact on keeping melatonin levels higher when worn despite exposure to bright light but that is far from conclusive evidence that they will make looking at screens late at night a benign habit.

So what do experts suggest, while we wait for further evidence as to how dangerous, if at all, our increased exposure to blue light is and what level of protection the various supplements and glasses provide?

The first step is to try and avoid looking at bright screens for 2 to 3 hours before bed. For those who do not have a choice, consider wearing blue-blocking glasses or installing an app that filters these wavelengths at night. Try to keep the screen 2 feet away (an arm’s length) and positioned so that you have to gaze slightly downward to see it. Use dim red lights for night lights as they have the least power to shift circadian rhythms and finally expose yourself to lots of bright light during the day