Aches and pains are familiar to all of us. When you touch the oven dish by accident, put out your back, or get a paper cut. However, imagine if that sharp, intense pain became chronic; lasting weeks, months, or even, years!
Chronic Pain
This is the case for 20% of the global population, who suffer from chronic pain. It is associated with numerous medical conditions, including, arthritis, degenerative disc disease, migraine, fibromyalgia and cancer. A study published in the Journal of Pain in 2012 placed the annual cost of chronic pain at $635 million in the U.S. This is more than the yearly costs for diabetes, cancer and heart disease.
Why Not Just Take a Pain Killer?
Pain killers, such as non-steroidal anti-inflammatory drugs (NSAIDs) or opiates, are effective for acute pain. Conversely, when used over longer periods, studies have shown that patients develop antinociception (tolerance to the pain-relieving effects). Furthermore, NSAIDs, such as aspirin, have been associated with damage to the gastro-intestinal tract, and opiates with addiction and drug withdrawal syndrome.
Devices
While opiates and NSAIDs modulate biochemical pathways involved in pain, several devices on the market target physical aspects of pain. For instance, transcutaneous electrical nerve stimulation (TENS), which affects the electrical signalling pathways, or ablation techniques, which physically damage the nerve to eliminate the source of the signal. However, these approaches are highly targeted; they are administered to a localized area of tissue, whereas, chronic pain is often rooted beyond the original source of pain. This presents a challenge for the use of these procedures in treating chronic pain on a broader scale.
A New Light?
Green light therapy may provide new hope for chronic pain sufferers. An exciting study, performed by researchers at the University of Arizona, found that rats with neuropathic pain demonstrated increased tolerance to thermal and tactile stimuli when bathed in green light.
In this study, green light was administered to the rats in several ways. The first group were exposed to light from green LEDs. A second group was exposed to ambient, room lighting, but the rats were also fitted with contact lenses allowing only green light to pass through. A control group was fitted with opaque contact lenses which blocked the green light from entering their visual system.
Both groups of rats that were administered with exposure to green light demonstrated beneficial effects on their pain threshold. The control group showed no such benefit. The effect of the green light therapy lasted four days and, significantly, no tolerance to the therapy was observed. In addition, there were no apparent side effects, motor or visual impairment.
A small, randomized, double-blind clinical trial to investigate the effects of green light therapy on patient with fibromyalgia has been initiated.
Why Green Light?
The mechanism for the effects of green light on pain perception are not clear. In an article, one of the senior authors speculates that green light may increase the levels of circulating opioids. However, he also states that further research is needed to substantiate this.
While it is known that there are photo-sensitive pathways within the body, the link with pain is not well established. Interestingly, the University of Arizona study was not the first to use light therapy for treatment of chronic pain. In fact, a search for interventional trials using light for treatment of chronic pain reveals 34 studies. The interventions range from a morning ‘bright light treatment‘ to treat chronic pain and PTSD, to the use of tinted spectacles to treat migraine. Positive results were also observed in a study, by Professor Thomas Tolle at Technische Universitat Munchen, investigating specially designed overhead lighting to treat chronic pain. Outside of chronic pain, the positive effects of bright green light therapy have also been observed in the treatment of depression.
Conclusions
Although the mechanism remains unclear, there is mounting evidence for the efficacy of green light or bright light therapy in a number of clinical conditions. Being a physical treatment, light therapy presents an attractive alternative to pharmaceuticals. It is low-cost, non-invasive, requires minimal specialist training to administer and demonstrates potential to treat chronic pain in a range of conditions. While more research is needed to validate this potential, the future may well be bright (light) for the treatment of chronic pain.
Image courtesy of pixabay.com
