Special Considerations for Severe ME/CFS: Light
Those with severe ME/CFS are highly subject to natural light deficiency. When too ill to leave home or worse, one’s bed, exposure to outside natural light is rare or an impossibility. Humans however are not meant to be deprived of natural light.
This article is part of a 3-part series on special considerations for severe ME/CFS.
Lack of natural light exposure has been associated with numerous health concerns including near-sightedness, depression, sleep disorders, memory problems, and more. Light deficiency can also quickly result in a vitamin D deficiency. All of these effects are believed to be due to the fact that light is essential for neurotransmitter function. Indeed vitamin D can act as a neurotransmitter and hormone, not just a vitamin.
Perhaps most importantly, exposure to light helps set the circadian rhythm. We learned in other posts how important training circadian clocks can be for metabolism and cellular inflammation. Indeed, lack of natural light has been associated with nighttime increases in the stress hormone cortisol, which can promote inflammation.
How Much Light?
Light is measured in the unit of Lux, which determines the intensity. To give some perspective to this measure, consider that a sunny day at noon can record up to 70,000 Lux. A dim night with a full moon averages 0.1-0.3 Lux. A candle burning 1 meter away emits 1 Lux. Your smartphone emits roughly 40 Lux.
Commercial light boxes aim to achieve light intensities mimicking direct sun exposure. These devices typically offer 10-12,000 Lux if used for about 10 minutes. Timing of light therapy is vitally important. Early morning light exposure helps entrain the circadian system for the day. A second session of light therapy in the late afternoon is also suggested to improve sleep onset.
Light therapy has long been used as a treatment option for seasonal affective disorder (SAD). It offers full spectrum light exposure through a small device that is simply placed near the person. Meta-analyses have shown the effectiveness of light therapy seasonally as well as non-seasonally for depressive symptoms. Just 30 minutes of light exposure is deemed effective for improving symptoms. These positive effects have also been observes in some studies with attention-deficit/hyperactivity disorder, delirium, and dementia. No consensus on timing, intensity, and duration is established.
The Power of Light Therapy
The profound effect of simple light therapy is most pronounced in the field of Parkinson’s. Parkinson’s disease is believed to be compounded by imbalance of melatonin and dopamine in the central nervous system. Several small studies have used light therapy to assess light’s effect on the motor symptoms of Parkinson’s, but also effect on sleep disturbance and mood. Following daily 1-1.5 hours of light therapy at an intensity of 1000-1500 Lux, given 1 hour prior to usual sleep time, there was improvement in sleep, mood, and reduced muscle rigidity. Some patients even reduced their dopamine medications! These effects were present in as little as 2 weeks of therapy.
Light therapy has the potential to improve sleep, reduce nighttime spikes in the stress hormone cortisol, and relieve depressive symptoms. Even if these symptoms do not drastically improve after a few weeks of light therapy, it is important that the home bound and bed bound patient maintain close to normal light exposure to mimic normal circadian rhythm phases. Without regular patterns of light exposure, over time the condition can worsen via vitamin D deficiency, stress hormone imbalance, metabolism problems, and neurotransmitter imbalances. This may be safely and easily mitigated via a daily routine of light therapy.
When Light Hurts
A percentage of severe ME/CFS patients have extreme sensitivity to light—photophobia. The idea of a light box therapy in these individuals may seem like a torture device. Dark sunglasses are often worn to reduce symptoms. Several studies examining photophobia, blepharospasm (excessive blinking), and migraine have concluded that not all sunglasses are alike. Lenses designed with FL-41 tinted lenses, a rose tint, are best at reducing these ocular symptoms. These findings have even been confirmed using functional MRI (fMRI).
Use of light therapy may still be beneficial when used carefully in photophobic patients. Body exposure to certain light boxes may increase vitamin D levels more than direct sunlight. The potential to safely deliver vitamin D without sun damage is of great interest. These devices must emit ultraviolet light, usually through LED’s, to activate vitamin D precursors in the skin. To prevent potential skin damage, this type of light therapy limits the band of UV light emitted. If these effects can be produced peripherally with light therapies, it raises the possibility of neurotransmitter and hormone effects without direct eye exposure to light.
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Prakash, C. et al. (2007) Treatment of vitamin D deficiency with UV light in patients with malabsorption syndromes: a case series. Photodermatol Photoimmunol Photomed. 23(5): 179–185.