Winter Months Spent in Sunny Climes Can Lower MS Risk, Study Suggests

Winter Months Spent in Sunny Climes Can Lower MS Risk, Study Suggests

Greater exposure to sunlight during the winter months — part of a person’s lifetime exposure to ultraviolet radiation — can help to lower the risk of multiple sclerosis (MS), a large U.S. cohort study suggests.

The study, “Lifetime exposure to ultraviolet radiation and the risk of multiple sclerosis in the US radiologic technologists cohort study,” was published in the Multiple Sclerosis Journal.

Increasing evidence suggests that poor exposure to ultraviolet radiation from sunlight, especially during childhood, is a potential risk factor for MS.

The mechanisms underlying this association are thought to be linked to the impact of the sun’s ultraviolet radiation on the immune system, or in the synthesis of vitamin D — whose deficiency is suggested to increase the risk of MS, although this connection was recently challenged.

“There is epidemiological evidence suggesting that low exposure to ambient UVR [ultraviolet radiation] during early life may be associated with MS and earlier symptom onset,” the researchers wrote.

To further investigate the link between ultraviolet radiation and MS, researchers analyzed people taking part in the U.S. Radiologic Technologists (USRT) study, a decades-long investigation into the health effects of potential low doses of radiation experienced by radiologic technologists.

A total of 39,801 participants also completed a series of questionnaires about places of residence and sun exposure — specifically, time spent outdoors on weekends and weekdays, history of sunburns and skin sensitivity to sunlight — and general health and lifestyle questions. The study also analyzed those with MS, including year of diagnosis.

Join the discussion in the MS Forums to learn more about this subject!

Among participants, there were 569 self-reported MS cases, with medical records available for 203 of them. A review by MS-specialized neurologists confirmed an MS diagnosis in 148 cases.

The study population was predominately female (more than 90%), with a mean age of 44 at MS diagnosis.

Researchers estimated the participants’ exposure to ultraviolet radiation by crossing residency information with satellite data from NASA’s Total Ozone Mapping Spectrometer (TOMS) project, launched in 1996 to measure ozone levels.

Results showed a trend for an increased risk of MS with lesser exposure to the sun’s ultraviolet radiation during winter months, but no effects were detected during summer months. The effects were consistent across groups younger than age 40.

While exposure to sunlight in summer is most likely sufficient for vitamin D production regardless of place of residency, areas where the sunlight is significantly poor during the winter poses a risk for vitamin D deficiency.

“Vitamin D targets nervous system tissues, regulating important neurotrophic factors in the brain, and also exerts effects on the differentiation and functioning of immune cells,” the researchers wrote.

Researchers also highlighted the potential effect of the ultraviolet radiation on the immune system independent of its role in vitamin D production.

“Our findings are consistent with the hypothesis that UVR [ultraviolet radiation] exposure reduces MS risk and may ultimately suggest prevention strategies,” the study concluded.


  1. Susan Stone says:

    This speaks of risk developing MS but does anyone know the data on the need for UV supplementation in winter for people who have already developed MS?

  2. Danielle says:

    We’re all using spf sunscreen when in the sun/dermatologists recommendation-how does that effect the bodies ability to absorb sun to increase vitaminD?

  3. Gwen Hamer says:

    I am thinking of moving somewhere sunnier (eg Spain although my Spanish isn’t great). I have 4 year-old twins so would need somewhere with international or bilingual schools for their future years. Have any of you MSers moved abroad (because you’ve got MS/ to get more sun and less stress) and would you recommend somewhere in particular?

  4. Greg says:

    Vitamin D is a good thing! I take a daily Vitamin D (D-3, 5,000 IU) supplement and a multivitamin that also contains Vitamin D. My chances of a “Greater exposure to sunlight during the winter months” is between slim and none and slim left town.

  5. Marc says:

    Yes, it has been known for many decades that regular, non-burning sun exposure is protective against MS, and it is also well-known that sun exposure protects against MS regardless of the vitamin D levels of the blood. Here are more positive effects of sun exposure:
    •Seventy-five percent of melanoma occurs on areas of the body that are seldom or never exposed to sun
    •Women who sunbathe regularly have half the risk of death during a 20-year period compared to those who stay indoors.
    •A Spanish study shows that women who seek the sun have one-eleventh the hip-fracture risk as those who avoid sun.
    •Men who work outdoors have half the risk of melanoma as those who work indoors.
    •Women who avoid the sun have 10-times the risk of breast cancer as those who embrace the sun.
    •Women who sunbathe regularly have half the risk of death during a 20-year period compared to those who avoid the sun.
    •Sun exposure increases nitric oxide production, which leads to a decrease in heart disease risk.
    •Sun exposure dramatically improves mood through the production of serotonin and endorphin.
    •Sun exposure increases the production of BDNF, essential to a properly functioning nervous system.
    More information: Or, read Dr. Marc Sorenson’s new book, Embrace the Sun, available at Amazon

  6. Sally Bartczak says:

    Yes I believe this hypnosis! I have had MS for 40 years and feeling better in summer. Also when I was younger and pregnant I felt great! If there is some way to trick my body to think was pregnant.

Leave a Comment

Your email address will not be published. Required fields are marked *

Pin It on Pinterest

Share This