Light Therapy for Chronic Pain

Out of the shadows, out of opioids, and experiencing less pain.

Posted Oct 30, 2017

Light. As it becomes less, we think of it more.

Lately and relentlessly, the daylight of our days is progressively truncated and we become a little more stuporous when the alarm rings each morning. We hear weather reporters telling us that daylight saving time ends this coming weekend and maybe, we think, there is hope for those like us. And then we realize it is all a shell game; the same dimming light is there, just shuffled around a bit. Add feeling foolish to whatever else ails us at this time of year including chronic pain, as research demonstrates that pain is experienced more intensely in the fall and winter

Nonetheless, give us credit. We try to make up for the lack of light with Halloween costumes, Thanksgiving feasts, and Christmas parties. It is not clear how effective these really are. After all, don’t suicides spike upwards during the holiday?

Perhaps all we need is what we need, light: the same light that is prescribed by the waning months of the year prescribed by the local health care provider.

As many know, light therapy has been used to treat depression, to increase daytime circadian stimulation, and to improve sleep quality Additionally, bright light has been shown to improve the mood of adolescents taking antidepressants compared with those without such light therapy.

Another study found that exposing patients to bright light of more than 6000 lux significantly improved seasonal affective disorder.

Light therapy may have psychological effects arising from physiological changes such as light’s ability to stimulate the release of an individual’s own natural opioids, which affect pain response or its perception.

Pain has sensory, cognitive, and affective dimensions. It has been shown by scholars, as well as known by those who suffer chronic pain, that the emotional state of patients significantly influences pain. The question begging to be answered in this age of prescription opioid abuse: How can patients be treated safely to improve the pain they experience? Can people be pain-free AND pill-free? 

Researchers recently reported on the effects of light-emitting diodes (LEDs), in the visible spectrum, on acute sensory thresholds in naive rats as well as in experimental neuropathic pain. Rats receiving green LED light (wavelength 525 nm, 8 h/d) showed significantly increased paw withdrawal latency to a noxious thermal stimulus. This pain-reducing effect persisted for four days after the last dose of LED light without the development of tolerance. No apparent side effects were noted. Despite LED exposure, opaque contact lenses prevented this pain-reducing effect of LED light. Rats fitted with green contact lenses exposed to room light exhibited a reduction in pain behavior, arguing for a role of the visual system. The researchers concluded that the pain reduction is likely due to increased opioid-like expression in the spinal cord. Naloxone (a drug which reverses the effects of opioids) reversed the pain-reducing effect of LED light, suggesting involvement of central nervous system opioid circuits.

Of course, the experiment discussed above used rats as subjects. It will be of interest to see if humans are similarly relieved of pain with LED light. Consequently, modulating the duration and intensity of light may prove useful in the clinical setting for reducing the use of opioids in pain management. Preliminary results indicate that light can benefit chronic pain patients.

In the meantime, open the shades, put your head right into that sunny morning, and wait for your body’s opioids to kick in.

References

Long-lasting antinociceptive effects of green light in acute and chronic pain in rats; PAIN 158 (2017) 347–360