There’s a good probability that some of your customers are either migraine sufferers, or they know of someone who is. How lighting is used may help – or worsen – the cause and effects of severe headaches.
As millions of migraine sufferers know, these aren’t ordinary headaches. Migraines are the second most common type of primary headaches and affect approximately 1 in 10 Americans and 10 percent of the world’s population. According to the National Headache Foundation, more than 28 million Americans suffer from migraines, with women three times more likely to have migraines than men — and if you have a close relative with migraines, you are much more likely to have them, too.
Experts believe migraines may be related to mutations in genes that affect certain areas of the brain. About 20 percent of children and adolescents also have significant headaches, with 5 percent of them suffering from migraines. While both boys and girls can get migraines, after puberty they are more common among females. Migraines are also more common among people who have epilepsy, depression, asthma, anxiety, stroke, and some other neurologic and hereditary disorders.
[mks_pullquote align=”left” width=”630″ size=”24″ bg_color=”#ffffff” txt_color=”#1e73be”] In this new study, the team found that a narrow band of green light causes significantly less discomfort in comparison to all light that migraine sufferers are exposed to. The study also indicated that green light can even reduce headache pain with exposure at low intensities. [/mks_pullquote] Did you know headaches are the most common cause of absenteeism from work and school? Migraine sufferers lose more than 157 million work and school days every year because of headache pain. Contrary to popular belief, migraines are not caused by tension, stress, or allergies, unlike other types of headaches. Rather, migraines are caused by changes in the nerves and quality of blood vessels referred to as vasoconstriction and vasodilation. This change in the blood vessels can cause extreme pain – and, often, an aura before migraine onset — which can result in sensitivity to light, smell, and sound.
While a direct, single-cause of migraine trigger is not yet known, there are theories that link the condition to certain things such as chemicals in plastic food packaging and flickering lights, as well as red wine. Different aspects of surrounding light can also affect those who experience migraines — and some may serve as triggers, while others only become a problem once a migraine attack has begun.
LIGHTING AS A TRIGGER
Light is a common migraine trigger, with approximately 40 percent of those who experience migraines having significant issues with light triggering an attack.
When discussing the potential impact, it is important to realize the difference between sensation and perception. “Sensation” refers to the physiological detection of external conditions that can lead to a nervous system response; “Perception” is the process by which the brain interprets the sensory information. Here are some of the ways that lighting serves as a trigger.
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The flicker in magnetic-ballast fluorescent lamps used in traditional office lighting has been linked to headaches, fatigue, blurred vision, eyestrain, and a reduction in visual task performance for certain populations.
INADEQUATE LIGHT LEVELS / COLOR TEMPERATURE: Inadequate lighting, light levels, and screen over-use can result in eyestrain, which is a known trigger. Consumers who are replacing their incandescent bulbs with CFLs or LED lamps often pay more attention to selecting the wattage versus the lumen output — which is a big mistake. (Watts measure the energy use, and not the light generated.)
Another consideration is color temperature. Choosing a Kelvin temperature in the 2700K range can emit warmer light in the more pleasing orange/yellow end of the color spectrum that is closer to that of most traditional incandescents. Lamps rated at 5000K and above emit a cooler blue to white light. It can be difficult to find the right balance between reducing light – when it is the culprit – without reducing it to the point where lack of light becomes the cause.
LIGHT-SENSITIVITY TRIGGERS: It is difficult to accurately identify triggers and contributing factors to migraines, but light sensitivity is a definitive cardinal feature of a migraine. One of the diagnostic criteria for this disorder is to avoid the detrimental effects of light by reducing both the intensity and duration of exposure during the onset of migraine symptoms. Exposure to bright light and glare, dazzle patterns, and flicker are all elements that exacerbate an existing migraine attack.
BRIGHT LIGHT: According to the Lighting Research Center, “Glare is a visual sensation caused by excessive and uncontrolled brightness. It can be disabling or simply uncomfortable. It is subjective, and sensitivity to glare can vary widely.” Bright Light –
whether it comes from the Glare of natural or artificial light – can be managed with the use of low-intensity bulbs or lamps with thick shades. Turn on lamps instead of overhead lights to create diffused light. However, keep in mind that it is possible to have a well-lit room without glare, and yet create a room that is uncomfortably bright.
DAZZLE: For some who experience light sensitivity as a symptom, exposure to bright patterns –
particularly checkered, striped, and zig-zag
patterns – can trigger or worsen a migraine. This is referred to as Dazzle. Experts suggest avoiding black-and-white or bright-colored patterns in flooring, furniture, and clothing. If this is a significant problem, migraine sufferers should check the decor of hotels in advance before reserving a room or ask for a room with neutral colors.
FLICKER: The most common trigger for a migraine attack is often caused by flickering lights. Flicker used to be a big issue in the age of CRT monitors and old fluorescent tubes when we would experience a flickering of the monitor and lamp. Flicker happens when light shines unsteadily or a light source changes from bright to dim quickly and repeatedly. Since LEDs do not have filaments, it was originally thought that there would be zero flickering with this new light source. Today’s modern screens and high-quality bulbs are mostly flicker-free as they refresh at a rate higher than 60Hz. Since the human eye and brain only detect light as flickering under 50Hz, it has definitely become less of an issue, however, it still requires attention of both the design community and consumer.
“Solid-state lighting has made great advancements in the lighting field, but there is still a need to be attentive to lighting quality and flicker as stroboscopic flicker has crept back in,” notes lighting designer Natalia Lesniak, Msc, LC, IES from Cooley Monato Studio.
Flicker characteristics can be visible, invisible, perceptible, and detectable (sensation)
✴ Sensation: External conditions are detected; neurons respond
✴ Visible flicker: Luminous modulation is sensed and perceived
✴ Invisible flicker: Luminous modulation is sensed, but not perceived
There are two common types of Flicker: Flicker as a repetitive change in magnitude over time or modulation of the luminous flux of a light source; and Stroboscopic effect, which is a luminous flux modulation perceived when objects are in motion. Visible Flicker can cause distractions and neurological problems such as epileptic seizure (1 in 4,000 people have photosensitive epilepsy ~3-~70Hz) and an increase in autistic behavior.
Invisible Flicker (Stroboscopic flicker) can result in: eyestrain, headache, migraine, stroboscopic effect (impacted motion perception), reduced performance (reading or other visual tasks), and disruption of security systems & security cameras. Low-frequency flicker can induce seizures in people with photosensitive epilepsy. The flicker in magnetic-ballast fluorescent lamps used in traditional office lighting has been linked to headaches, fatigue, blurred vision, eyestrain, and a reduction in visual task performance for certain populations. Flicker can also produce hazardous phantom array effects, which may lead to distraction or the apparent slowing or stopping of moving machinery in an industrial setting.
According to the U.S. Department of Energy, LED flicker characteristics are primarily a function of the LED driver. The LED flicker and dimming performance depends on the LED driver as the use of dimmers and other electronics can induce or increase flicker.
Dimming an LED source can increase or induce flicker, most notably when phase-cut controls are used and/or pulse-width modulation (PWM) is employed within the driver to reduce the average light output from the LED source. Most LEDs are connected to the AC mains that operate at 50 or 60 Hz in different areas of the world. Even after rectification to frequencies of 100 or 120 Hz, any line-associated flicker may be detectable by the human eye due to the relatively low frequencies involved. The rectified line may lead to Strobe Flicker, which is more prevalent to lead to distress in humans.
“It’s not the source that is the problem,” Lesniak explains. “It’s not the LED lamp; it is how we run them, as LEDs do not inherently flicker.”
The IEEE addresses the health effects of flicker in its current recommended practices published and updated in 2016: IEEE Recommended Practices for Modulating Current in High-Brightness LEDs for Mitigating Health Risks to Viewers. The IEEE report indicates that the health effects of flicker can be divided into those that are the immediate result of a few seconds’ exposure – such as epileptic seizures – and those that are the less obvious result of long-term exposure, such as malaise, headaches, and impaired visual performance. According to a report by IEEE and Pacific Northwest National Laboratory, the LED products that are most likely to flicker are:
➤ AC LEDs
➤ DC LEDs with simple/inexpensive drivers (e.g., inadequate capacitors)
➤ Integral lamp LEDs on some electronic transformers
➤ LEDs dimmed with phase-cut dimmers (triac, e.g.)
➤ LEDs with Pulse-Width Modulation (PWM) drivers
“Most fixtures on a switch circuit can have issues when placed on dimming,” Lesniak states, adding, “As you lower the dimmer, the fluctuation dramatically changes.”
In the absence of flicker metrics and waveforms, specifiers can pursue qualitative means for evaluating flicker. They can consider how the risk of flicker-related problems is heightened or reduced by a given light source, the type of space, its occupants, and the tasks being performed.
LED systems should always be visually evaluated, ideally with flicker-sensitive clients. Waving a finger or pencil rapidly under the LED source, or spinning a flicker wheel, can expose the presence of flicker through the stroboscopic effect — even for those who are not naturally sensitive. Low-flicker sources should always be used for both ambient lighting and task lighting in offices, classrooms, laboratories, corridors, and industrial spaces. Minimizing flicker is especially important where susceptible populations spend considerable time, such as hospitals, clinics, medical offices, classrooms, and daycare centers.
GREEN LIGHT MIGHT REDUCE SEVERITY
A new study, led by researchers at Beth Israel Deaconess Medical Center (BIDMC) and published in Brain (a journal of neurology published by Oxford University Press) has found that exposing migraine sufferers to a narrow band of green light significantly reduces photophobia and can reduce headache severity.
In earlier research, Rami Burstein and his colleagues discovered that blue light hurts migraine patients who are blind. This finding prompted the initial thinking that abnormal sensitivity to light during a migraine could be alleviated by blocking blue light. In this new study, the team found that a narrow band of green light causes significantly less discomfort in comparison to all light that migraine sufferers are exposed to. The study also indicated that green light can even reduce headache pain with exposure at low intensities.
The researchers asked patients experiencing acute migraine attacks to report any change in headache when exposed to different intensities of blue, green, amber, and red light. At high intensity of light – such as a well-lit office – nearly 80 percent of patients reported intensification of headache with exposure to all colors but green. They found that blue and red lights generated the largest signals in both the retina and the cortex and that green light generated the smallest signals. Moreover, the researchers found – unexpectedly – that green light even reduced pain by about 20 percent.
It can be difficult to determine the exact trigger of a migraine as triggers differ from person to person. Eliminate flicker, glare, dazzle, and badly positioned lighting first to reduce the potential for triggers caused by lighting. Invest in good quality new bulbs and test if they flicker before using them. Note that older compact fluorescent bulbs can also flicker. If you don’t know how old the ones in use are, replace them to see if that fixes the problem. If you use LED lighting, we know that LEDs will not flicker if given a steady DC current — but when AC current (mains) is converted to DC, a capacitor is normally used to smooth the output. If the capacitor isn’t working, or the transition isn’t done well, it can result in LED lights that do flicker. For more information, review the resources available at the U.S. Department of Energy and the IEEE.