Written by Seamus Flynn, Optometrist
Most of us have experienced headaches and a throbbing sensation after a long day starting at screens but is this caused by the blue light radiating from our digital devices?
Headaches and migraines are often triggered by exposure to certain types of light. In fact the link between light and headaches are well established both as a cause and a symptom of migraines in particular.
Photophobia, or an aversion to light, is a very common symptom of migraines and one which can be debilitating enough that the suffer needs to find a dark room to lie down in until the symptoms subside.
It is though that migraines and photophobia results from light traveling from a pathway from the eyes to an area of the brain called the cortex. Blue light has been shown to activate these pathways that lead to migraines much more than green light for example which activate the pathway to a much lesser extent.
The wavelength of light that appear to activate it the most is at 480nm (nanometers) of blue light.
A study (1) from the university of Utah set out to specifically block blue light wavelengths at the 480nm level to assess the affect this had on migraine suffers. The study found that by blocking this blue light wavelength that the participants reduced the impact of their light triggered migraine by wearing blue light blocking glasses.
Blue light can also cause headaches indirectly through eyestrain. These wavelengths are shorter, high energy wavelengths and are the closest wavelengths in the visual spectrum to the harmful UV rays ,The reason why UV rays are damaging to the eye is that they are also high energy wavelengths and can cause oxidative stress to the cells in the eye. Although the blue wavelengths have slightly less energy, the principle of why this causes a stress to the visual system is the same. This stress leads to eyestrain and the link between eyestrain and headaches is well established.
Another cause of this eyestrain is the fact that the eyes natural resting point of convergence is around 80cm away. This is the point at which the eyes intraocular muscles that control movement and ciliary muscles that control the movement of our internal lenses are completely relaxed and are not contracting or working to clear our vision or move our eyes in or out. When we look at screens they are usually closer than this at around the 55cm distance so our eyes are never relaxed whilst looking at the screens and our eye muscle are constantly constricting and relaxing to clear our vision and converge our eyes inwards which naturally occurs at close distances.
HOW TO PREVENT HEADACHES AND EYESTRAIN WHILST USING DIGITAL SCREENS
Wearing blue light blocking glasses that block out the high energy wavelenghts of light is a great way to reduce stress on the visual system. Other things you can do include
1. Place the monitor in a position that reduces glare on the screen.
Glare reflecting from your screen causes eyestrain but in addition to this also results in movements your head and body naturally make to avoid the glare and these positions can cause us to take up awkward positions that can result in posture issues. Having blue light glasses that also have an anti glare coating helps avoid this
2. Place the monitor away from or at right angels to windows and task light sources.
The position of light sources has a direct impact on the glare from the screen and eyestrain caused. In some situations it may be difficult to adjust the light source so you can try closing a blind or adjusting the brightness on the monitor to match the background lighting level.
3. Position the monitor directly in front of you
This helps with your posture and prevents awkward head and body movements that cause cause postural issues as well as eyestrain.
4. Place the top of the screen at eye level of or slightly (0-30 degrees) below eye level.
According to ergonomics expert and professor Dr. Alan Hedge, “When you are seated comfortably, a user’s eyes should be in line with a point on the screen about 2-3″ below the top of the monitor casing (not the screen). Sit back in your chair at an angle of around 100-110 degrees (i.e. slight recline) and hold your right arm out horizontally, your middle finger should almost touch the center of the screen. From that starting position you can then make minor changes to screen height and angle to suit. Research shows the center of the monitor should be about 17-18 degrees below horizontal for optimal viewing, and this is where it will be if you follow the simple arm extension/finger pointing tip. You actually see more visual field below the horizon than above this (look down a corridor and you’ll see more of the floor than the ceiling), so at this position the user should comfortably be able to see more of the screen. If the monitor is too low, you will crane their neck forwards, if it’s too high you’ll tilt their head backwards and end up with neck/shoulder pain.”
5. Place the monitor at least an arm’s length away from you.
The monitor should be at a comfortable distance away from you, allowing you to view the entire screen without too much twisting of your head and neck.
6. Place the monitor so you can clearly read the screen without bending your head, neck or trunk forward or backward.
By now you’ve probably noticed a common theme. You need to place your monitor to reduce awkward postures. Get your monitor in the right position and your neck and shoulders will thank you!