CFL 'flicker' and photosensitive epilepsy, Ménière's disease and migraines.
Concerns have been raised that compact fluorescent lamps (CFLs) may have adverse impacts on the health of some people. One such concern is the effects of CFL 'flicker' on sufferers of photosensitive epilepsy, Ménière's disease and migraines.
Compact fluorescent lamp (CFL) 'flicker'
As part of their normal operation fluorescent lamps flash on and off very rapidly – CFLs ‘flicker’ at a rate of more than 20,000 times per second, modern linear fluorescent tubes at more than 5000 times per second, and older style linear fluorescents at 100 times per second. These rates of flickering are well above the level detectable by the human brain.
Occasionally, fluorescent lamps may develop a fault which may cause them to have a noticeable flicker – these lamps should be replaced.
Photosensitive epilepsy is the name given to epilepsy in which all, or almost all, seizures are provoked by flashing or flickering light, or some shapes or patterns. Both natural and artificial light may trigger seizures. Various types of seizure may be triggered by flickering light. Photosensitive epilepsy is rare and only 5 per cent of epileptics are diagnosed with this form of epilepsy.
Some known triggers for people with photosensitive epilepsy are:
- watching television or playing video games
- having a faulty lamp or television that flickers
- strobe lights
- driving at dawn or dusk with sun shining through a line of trees
- sun flickering on water
- looking out of the window from a fast moving vehicle
- geometric patterns.
More information about photosensitive epilepsy is available from Epilepsy Action Australia.
The frequency of flashing light most likely to trigger seizures varies from person to person. Generally it is between 8-30 Hertz (Hz) or flashes per second. CFLs ‘flicker’ at a rate well above this sensitive range (over 20,000 Hz) and do not pose a hazard to sufferers of photosensitive epilepsy.
Researchers have concluded that CFLs are no more likely to be a greater risk to people with photosensitive epilepsy than other lamps. Further, the Light Sensitivity Report (PDF 420 KB) by the Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR), revealed that:
“while photosensitivity of epileptics is scientifically proven, seizures induced by flicker can be accurately correlated to the frequency only for a small range (3 Hz, 15–18 Hz). Therefore, there is no scientific data that fluorescent lamps, including compact fluorescent lamps (CFLs) induce seizures.”
Epilepsy Action Australia suggests that fluorescent lights should normally not cause a problem for photosensitive epileptics, except when using faulty lamps which may flicker at a lower frequency visible by the human eye. In addition, much higher risks are connected with television and video games.
Ménière's disease afflicts about 0.2 per cent of the population. It is a condition where excess fluid in the inner ear upsets the ear’s balance and hearing mechanisms. This produces symptoms such as vertigo (dizziness), tinnitus (ringing in the ears) and hearing loss. The disorder usually affects only one ear and is a common cause of hearing loss.
There is no scientific evidence to suggest CFLs (or any fluorescent lights) can exacerbate or initiate symptoms of Ménière's disease. There are however, anecdotal reports that sufferers of Ménière's disease are more sensitive to flashing lights than others (because of their impaired balance systems), and so may be more susceptible to a phenomenon known as flicker vertigo.
Flicker vertigo may arise from flicker rates in the range of 4–30 Hertz or 4–30 times per second. Symptoms range from vague and non-specific feelings of unease through to nausea, dizziness, migraines, unconsciousness, and even photosensitive epileptic seizures. Flicker vertigo can reportedly affect anyone, but some individuals may be more susceptible than others. Triggering events can be as simple as viewing fast moving objects (such as fan blades, helicopter blades or a tree line from a moving car) that intermittently obscure the sun, creating a flickering effect.
CFLs ‘flicker' at a rate well above that detectable by the human brain and so should not affect Meniere's sufferers.
Migraine is one of the most common diseases of the nervous system. In developed countries migraine affects about 10–15 per cent of people. Migraines can be triggered by many different things, including stress, exercise, certain foods, bright light, flickering light, loud noises, strong smells, lack of sleep or too much sleep. In women, attacks may be triggered by hormonal changes, for example during menstruation.
If light is suspected as the triggering event for migraines, ordinary headaches, or even eyestrain, the primary cause is likely to be glare, highly contrasting, or inappropriate light levels. These problems are a result of poor lighting design rather than a feature of fluorescent lamps and can occur with any lighting technology if used inappropriately. Light fittings that enclose lamps and distribute light evenly without compromising light output and efficiency can help avoid these problems.
The UK migraine action association recommends:
- ensuring that lighting is adequate and well positioned
- fluorescent lighting should be properly maintained to minimise flicker
- fluorescent lamps should be fitted with the correct type of diffuser to imitate natural daylight as much as possible
- avoid reflected glare from shiny/polished surfaces, plain white walls etc, opt for matt finishes and break up surfaces with pictures, posters or plants
- fit adjustable blinds to windows.
While light sources with a detectable flicker can trigger migraines in susceptible individuals, CFLs 'flicker' at a rate well above that detectable by the human brain and so should not affect migraine sufferers.
Alternatives for individuals with photosensitive epilepsy, Ménière's disease or migraines
It is important to note that CFLs are not being mandated. More efficient forms of incandescent lighting will continue to be available, such as mains voltage halogen (MVH) lamps. MVHs have a very similar appearance to the traditional incandescent light bulb, can be used in all of the same fittings, and are readily available. The halogen gas they contain allows them to operate at a higher temperature, which results in higher efficiency levels. However, MVHs are not as energy efficient as CFL alternatives.
When changing from an inefficient incandescent lamp to a more efficient alternative, make sure that you select a product with an equivalent light output (or brightness) to the lights you already have in your home. The light globe conversion table is designed to assist you in your selection of a more energy efficient lighting alternative that best suits your lighting requirements.
As the phase-out of inefficient light bulbs progresses, the Australian Government will continue to consider health issues and examine options to address any significant concerns. This may include providing information about possible impacts on sufferers of photosensitive epilepsy, Ménière's disease and migraines, and/or information about new and emerging lighting alternatives.
Source: Australian Government Departmaent of Industry