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Lower sunlight exposure may increase stroke risk
February 1st, 2012
04:48 PM ET

Lower sunlight exposure may increase stroke risk

People who live in areas with the least amount of sunlight may have a greater risk for stroke, according to findings presented at the American Stroke Association’s International Stroke Conference in New Orleans this week.

Strokes occur when blood and oxygen is cut off from the brain due to a blood clot or a burst blood vessel. Stroke is the fourth leading cause of death in the United States and the number one cause of disability, according to the American Stroke Association.

What’s unique about this study, explained professor Leslie A. McClure, a biostatistician from the University of Alabama at Birmingham, is that her team used NASA satellite and ground monitor data to determine sunlight and temperature exposure and how it corresponded with the stroke risk of study participants.

When the different factors were compared, McClure said they found that people who had less than the midpoint level of sun exposure were at 60% increased risk for stroke. The study also confirmed previous findings that both hot and cold temperature exposure is associated with higher stroke incidence.

The UAB researchers used data from the REGARDS (REasons for Geographic and Racial Differences in Stroke) project, a long term study that includes more than 30,000 Caucasian and African American participants, age 45 and older. The study is funded by the National Institutes of Health.

McClure was quick to point out that more research needs to be done to confirm the results of the study, and to determine why sun exposure seems to be associated with reduced stroke risk.

She hypothesizes that vitamin D, which is produced when our bodies are exposed to sunlight, may help explain the association. Previous research has associated lower vitamin D levels with stroke and heart attack risk.

McClure also pointed out that “moderate but safe sun exposure” may be a part of the equation for preventing strokes, along with modifying known stroke risk factors, which include smoking, obesity, diabetes, high blood pressure, physical inactivity and high cholesterol.


soundoff (28 Responses)
  1. i believe it.

    I do think that's interesting. sunlight might have an interesting role in our health. i could see it.

    February 1, 2012 at 17:57 | Report abuse | Reply
    • i believe it.

      could be vitamin d. but sunlight at a certain amount of LUX can suppress hormones also. it suppresses the hormone that gives you the urge to sleep. i have to think about it now. maybe melatonin...i don't remember now. seems like it started with an s. i don't think we are very far along on the allergy path or the hormone path. but i suspect a lot will come out when we do.

      February 1, 2012 at 18:03 | Report abuse |
    • i believe it.

      seems like there's a lot of inflammation on the allergy route. i could see that leading to heart attacks. not sure about strokes. grain seems to raise blood pressure. exercise probably clears it out of our system faster.

      February 1, 2012 at 18:05 | Report abuse |
    • i believe it.

      i could see grain raising blood pressure (possibly on the allergy route) and that could lead to strokes. not sure what sunlight would have to do with it. unless people get outside more when its sunny and move around so they clear the grains out of their system faster maybe.

      February 1, 2012 at 18:07 | Report abuse |
    • KumQuat

      Sinlight is good for your eyesight, too. It's hard to see without it.

      February 2, 2012 at 00:04 | Report abuse |
    • Don

      "Lower sunlight exposure MAY increase stroke risk". I don't believe it! Interesting but I believe WRONG. I had a friend that wintered in Arizona every years for over 30 yrs exercised daily while there. At home when the weather permitted he did same thing and we get lots of sun where I live . He got a stroke then in a few years Dementia set in.

      February 2, 2012 at 15:06 | Report abuse |
    • CatSh

      Serotonin is the opposite of melatonin

      February 2, 2012 at 20:40 | Report abuse |
  2. i believe it.

    i doubt the grain industry, or pharma would ever let people know that though. i can't pee when i eat grain. took me years to figure that out. of course it keep blood pressure too high if you can't pee. then they tell people not to eat salt. so how are you going to get the excess fluid off...if you don't know that its grain that's causing the problem? i had to stop listening to them and start over. my blood pressure straightened out when i stopped eating grain.

    February 1, 2012 at 18:20 | Report abuse | Reply
  3. i believe it.

    try looking at grains and its effect on blood pressure. have people stop eating grain for about three days and see if they can pee again. (do they lose the diabetic symptom of frequent urination in small amounts? i did, but i'm only one me) i suspect you would get a LOT of information there. i agree that sunlight is in there somewhere...but not sure exactly how yet.

    February 1, 2012 at 18:25 | Report abuse | Reply
    • i believe it.

      i also don't know how much is attributed to genetically modified grain. i tested for allergies to corn, but my real life response is MUCH worse. i would say thousands of times worse. i didn't know if that was because the test might be corn, but in real life we get genetically modified corn? i'm sure it would kill me just because i didn't know what it was for so many years and it was chronic because they don't tell you what they put corn in. (AMA said they didn't have to. i think they are just trying to make more money off of us for the doctors. i don't think they care about our health very much.) sometimes you would swear they are just trying to make us sick so they can sell more drugs that don't work and get more doctor visits out of us.

      February 1, 2012 at 18:30 | Report abuse |
  4. John W.

    Sunlight is good for us. We are adapted to having it available. Want Vitamin D? Get sun. Who know what other benefits come from a little sunlight. Now, a full day in Mexico on a boat will make your skin peel of.. the toxicity, again, is in the dose.

    February 1, 2012 at 18:27 | Report abuse | Reply
    • i believe it.

      the IV vitamin D might have problems. real sun would probably be better.

      February 1, 2012 at 18:31 | Report abuse |
    • Dr Peter

      @ I believe - vitamin D comes in oral forms. it's not commonly given 'IV' hahahaha.

      anyway I dont think you can automatically say that the 'naturally made' vitamin D (from sun exposure) must be better because it's natural. The skin cancer you get from over exposure, that's natural too you know.

      February 1, 2012 at 23:00 | Report abuse |
  5. Paul

    What a junk study! People who have less exposure to sunlight may be less active, and less active people are more at risk of stroke (they might even be less active simply because they are more stroke-prone). So lack of sunlight is only associated with the stroke, not "increasing it". Under the pressure of "publish or perish", those researchers continuously conduct such convenient, easy, junk analysis, like the infamous Australian study which concluded that frequent masturbation at youth can decrease the risk of the prostate cancer!

    February 1, 2012 at 18:36 | Report abuse | Reply
    • Rob

      I dunno. You see, where I live we get little sun all winter long, many times not in fall or spring either. Yet people are still active, into sports, athletics, etc. So I'm not sure we can jump to conclusion that we can equal low sun exposure with low activity in the dark areas of the world....

      February 1, 2012 at 21:38 | Report abuse |
    • Hatixhe

      Grey sky is depressing, where I live is cold and people stay home and watch TV on their spare time after long day at work. When Spring comes and the day is longer and brighter, you can see way more people walking their dogs, running, etc. Me included. I walk to downtown when the weather is nice and I take the car when it is not.

      February 2, 2012 at 10:36 | Report abuse |
    • bobo

      the sun screen companies paid cnn to write this article

      February 2, 2012 at 15:31 | Report abuse |
  6. hamsta

    Just more evidence that you shouldnt listen to a government that spent a generation telling you to use marjarine instead of butter only to ban transfat.

    February 1, 2012 at 19:51 | Report abuse | Reply
  7. Epidemiologist

    I've worked with data from the REGARDS study myself and was lead author on a poster presented at the Council of State and Territorial Epidemiologists annual conference within the past few years. The Stroke Belt receives plenty of sun, and has the highest incidence of stroke in the U.S. However, the authors of this study do not even factor that into their work. Just because a person lives in a geographical area of low sunshine does not account for his or her own personal exposure to the sun. McClure should not be postulating about the vitamin D levels without taking actual measurements. I have regular vitamin D checks myself, the test is inexpensive and covered by insurance.

    February 1, 2012 at 20:00 | Report abuse | Reply
  8. Rob

    Very interesting. I definitely supplement vitamin D. And thank you for using the word 'caucasian' instead of 'white'...

    February 1, 2012 at 21:34 | Report abuse | Reply
  9. The_Mick

    People who live in areas with the least amount of sunlight live in cold areas where not much time is spent outside, on average, in Winter. Besides decreased Vitamin D, there's decreased exercise and decreased fresh air. My sinuses were stuffed last week then the weather warmed. I went bicycling for an hour and a half Sunday in 50F weather and two hours Tuesday in 60F+ weather. My nasal passages are dry and wide open now.

    February 1, 2012 at 23:46 | Report abuse | Reply
  10. Beefburger

    @i believe it, I think not eating grains makes you sound like "Rain Man".

    February 2, 2012 at 01:49 | Report abuse | Reply
  11. monkeyman

    So obtain skin cancer or have a stroke,.. hmm. which should I choose?

    February 2, 2012 at 02:29 | Report abuse | Reply
  12. Myto Senseworth

    Which one can the medical community make the most money of of, skin cancer or strokes?

    February 2, 2012 at 15:29 | Report abuse | Reply
  13. Jorge

    When I lived in the tropics outside the U.S. I craved being active, outside and awake. I took deep breaths, took long steps and seldom had aches and pains. Then I came back, and during the winter I rub my joints, soak my head to drive the cobwebs off and remember why I was so miserable in NYC as a child. Oh God, can't wait to retire and go back.

    February 3, 2012 at 08:58 | Report abuse | Reply
  14. sunny d

    good thing I lived 30+ yrs in Florida, the SUNSHINE state!

    February 3, 2012 at 12:46 | Report abuse | Reply
  15. Cryo

    The notion that sunlight plays a factor in strokes is ridiculous. It is just scientists wasting the money that people donate. If the same group studying this stupid theory were to have been researching something real, then they would be finding out that microwaves can be used to cure Alzheimer's disease, instead of some solitary school girl experimenting on mice.

    February 13, 2012 at 05:24 | Report abuse | Reply
  16. trendsworld

    Heart Strokes in Youth increased for more information

    http://www.trendsfair.com/heart-strokes-in-youth-increased/

    The percentage of heart strokes in the people are increasing
    day-by-day especially in the young people because of their food habits.
    In 1993, the heart strokes were 13% among the people aged below 55 and
    now the percentage increased to 18%in…

    January 22, 2013 at 09:09 | Report abuse | Reply

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Get a behind-the-scenes look at the latest stories from CNN Chief Medical Correspondent, Dr. Sanjay Gupta, Senior Medical Correspondent Elizabeth Cohen and the CNN Medical Unit producers. They'll share news and views on health and medical trends - info that will help you take better care of yourself and the people you love.