Rowan Jacobsen
Can Sunlight Cure Disease?: Sunshine seems to calm down immune system disorders such as multiple sclerosis and type 1 diabetes. Now scientists are turning this discovery into treatments
https://pubmed.ncbi.nlm.nih.gov/40392731/
No abstract available
-----------------------------------------------------------------------------------
-----------------------------------------------------------------------------------
May 20, 2025
Can Sunlight Cure Disease?
https://www.scientificamerican.com/arti ... -diseases/
Sunshine may hold healing rays for a variety of autoimmune diseases such as multiple sclerosis. Scientists are turning this surprising discovery into treatments
Every morning Kathy Reagan Young steps out of the shower in her Virginia Beach home, towels off, dons a pair of protective goggles and stands nine inches from a light box the size of a small space heater. Young presses a button, and the box’s bulbs begin to glow a ghostly purple. She briefly bathes her torso in the ultraviolet rays coming from the bulbs, four minutes per side. Then she goes about her day.
That Young can have an ordinary day is remarkable. In 2008 she was diagnosed with multiple sclerosis (MS), a terrible malady in which the body’s own immune system attacks the sheaths that insulate the nerves, destroying them bit by bit. Symptoms begin with weakness, spasms, vision and speech problems, intense fatigue, and what Young calls “cog fog”—chronic low-grade cognitive impairment. Flare-ups can lead to periods of motor-control loss and paralysis. Young, an advocate for MS patients and creator of a popular podcast, has suffered through many such episodes. But things improved with the arrival of her light box.
Ultraviolet (UV) light boxes, which emit only a narrow bandwidth of light that is not linked to skin cancer, have been used for years in the treatment of psoriasis. Young got a prescription from her doctor, and the box was sent to her by a medical-device company called Cytokind that is hoping to expand such use to MS and other autoimmune diseases and was looking for some practical patient feedback. She tried out the device and gave them some pointers: make it smaller and easier to hold because MS often makes your hands go numb, and build in timed reminders to overcome the cog fog. Then, to her surprise, she found that her fatigue disappeared a few months after she started using it.
For years Young had been forced to rest in bed many times a day, but that stopped with what she calls her UV-fueled rebirth. “I was in a meeting, and someone said to me, ‘Wow, you seem like you’re pretty high energy!’” Young says. “And I guess I hadn’t really thought about it. And then two days later my daughter said to me, ‘Mom, what are you on?’ I think we were all a little surprised by how quickly and definitively it happened.” Her MS Disease Activity (MSDA) score, which rates MS severity based on the levels of key inflammatory molecules in the blood, was a 1 out of 10, the best possible score, and it has stayed low for more than a year. MS has no cure, and Young still suffers from transient pain and tingling, but the return of her vitality has made it all more bearable. “It’s incredible,” she says. “My friends used to invite me to things, and I’d say yes, but I always canceled because I was wiped out. Well, not anymore.”
Young is one of the first people in the U.S. to test UV phototherapy as an MS treatment, but she may be at the forefront of a revolution in how we think about light and a huge class of diseases. Autoimmune diseases such as MS and type 1 diabetes occur when our natural defenses—our immune systems—viciously turn against our own bodies and organs. These illnesses are estimated to affect more than 350 million people worldwide. Treatments have been elusive.
Recommended Stories
Although only a handful of clinical trials for MS light therapy have been conducted in people, evidence from a number of medical studies now shows that UV light, the highest-energy part of the solar spectrum that reaches Earth’s surface, has a surprising ability to calm an immune system that has bolted out of control. The new studies offer tantalizing hints that UV therapy might also work for other autoimmune diseases such as type 1 diabetes, rheumatoid arthritis, Crohn’s disease and colitis. All are more common in people who get very little sun exposure, as are maladies such as Alzheimer’s and cardiovascular disease that appear to have some immune system and inflammatory connections.
Now scientists are hoping to decipher the pathways through which UV light causes the immune system to back down from its alarm state. They are tracking the way molecules in the skin such as urocanic acid and lumisterol—which can affect immune system activity—respond to a shot of photons by triggering a cascade of signals that reach every organ in the body. Advocates say this work might lead to a blockbuster drug, an Ozempic for autoimmunity.
“UV light calms inflammation in the skin, the nervous system, the pancreas and the gut. Its potential is not fully realized.” —Prue Hart, Kids Research Institute Australia
Scientists not involved in the light research are more cautious, but they agree that something important is going on. “UV light therapy holds promise,” says Annette Langer-Gould, an MS researcher and neurologist at Kaiser Permanente in Los Angeles. But she would like to see rigorous and larger trials on various diseases and a better understanding of the mechanism.
That kind of confirmation could also solve a mystery that has vexed scientists for more than a century: Why do people living in lower-light environments have such high rates of disease?
The trail that led scientists to the discovery of UV light’s beneficial effects began with the confirmation of its dangers. In 1974 pioneering researcher Margaret L. Kripke (who would go on to found the department of immunology at MD Anderson Cancer Center in Texas) discovered that she could induce tumors in the skin of mice by exposing the rodents to UV light. But those tumors failed to grow when transferred to the skin of a different mouse. The new host’s immune system quickly eliminated them. Ten times she tried, and 10 times the tumors were squelched. When she suppressed the new host’s immune system with drugs, however, the tumors took hold. “That was the key!” she later recalled.
But why was the tumor able to grow in the original irradiated mouse? Was the UV light that had induced it also somehow suppressing the mouse’s natural immune response? In a series of experiments, Kripke determined that UV radiation was indeed a double whammy. Not only did it damage DNA in skin cells and trigger mutations that could lead to cancer, but it also suppressed the immune system’s surveillance of the skin, preventing that system from killing any budding cancers. This finding was a breakthrough in our understanding of how skin cancer develops, but it also seemed nonsensical from an evolutionary perspective. How could it possibly be beneficial for our immune system to relax in the presence of a common carcinogen?
It turns out that immune cells in our skin evolved to walk a fine line. As our primary interface with the outer world, the skin is barraged with potential stressors: heat, cold, wounds, bug bites, mysterious microbes of all kinds. For the first million years that our nonape ancestors spent under tropical African skies, solar radiation was the most common stressor of all. “It’s a challenge to the body,” says Prue Hart, an immunologist at the Kids Research Institute Australia who has been studying the effects of sunlight on immunity for more than 30 years. “It’s the most important environmental insult we have. We evolved to cope with it.”
Sign Up for Our Daily Newsletter
By giving us your email, you are agreeing to receive the Today In Science newsletter and to our Terms of Use and Privacy Policy.
But if the immune system had reacted to every kiss of sunlight with a full-throated attack, Hart says, we’d have lived in a constant state of inflammation, beset by rashes, hives and cutaneous autoimmune disorders. Instead the system learned to hold its fire.
In prehistoric times, this was the right approach. The damage was usually minor, the skin repaired itself, life went on. The trade-off—especially now that people live long enough for slow-growing tumors to get big and spread to other parts of the body—is that every so often a skin cancer sneaks through. One fascinating confirmation of this idea is polymorphic light eruption (PLE), a common disorder in which patients’ immune systems are not suppressed by sunlight. PLE sufferers develop itchy rashes and plaques after sun exposure, but they are less likely to develop skin cancer.
Dot chart plots multiple sclerosis prevalence data by latitude from 407 papers originally published between 1923 and 2018. In general, prevalence data goes up with distance from the equator.
.............................................................
.............................................................
https://www.cytokind.net/
We offer FDA-cleared NB-UVB lights to reduce inflammation naturally, presently cleared for dermatological conditions.
Women in front of a UVB Light
Reducing inflammation and improving outcomes in psoriasis for decades.
These lights have also been used in clinical trials for other auto-immune diseases: MS, COVID-19, and GvHD, etc.
----------------------------------------
----------------------------------------