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Do SAD Lights Cause Cancer?

By HERWriter
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I was chatting with my friend Linda about how depressing northeastern winters are due to the long stretches of gray gloomy days. I commented that, “Maybe one of those SAD (seasonal affected disorder) lights would help.” Linda, who is very fair complected responded, “I wonder how those lights even work, I would be reluctant to use one if they increased your risk of skin cancer.”

Funny she would think that because as I searched for information on SAD lights, another person posted in a forum that they had avoided using SAD lights because they were concerned about cancer. How do SAD lights work and is there a risk?

Seasonal affected disorder is a type of depression that occurs each year commonly during the fall/winter months. People experience depression with fatigue, lack of energy and an increased desire to consume carbohydrates. SAD is believed to affect over 14 million Americans, the majority being women. The cause is unknown but is thought that reduced sunlight affects the internal clock (circadian rhythm) in the body.

Light therapy is believed to work by altering the body’s circadian rhythm. Increased light acts to reduce melatonin levels that may contribute to feeling fatigued and de-energized. The increased light also acts to increase serotonin levels which reduce feelings of depression.

Current studies do show that light therapy successfully treats SAD symptoms and mental health professionals recommend using SAD light treatments for those believed to suffer from this condition. Light therapy can help people in as little as one week after starting therapy but SAD symptoms will return if the light is stopped for longer than a few days.

SAD lights are extremely bright lights. Their intensity is measured in “luxes”. A common treatment is 15 to 30 minutes from a 10,000 lux light box positioned approximately two feet from the person. What surprised me was that SAD lights work by stimulating the brain from light reaching our retinas through our eyes, not from exposure of the light to our skin. It is not recommended that a person look directly at the light but to just look at surfaces illuminated by it.

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Thanks Diane. Actually if it hadn't been for my friend, I would not have thought there was a cancer risk either. Let us know if you end up trying one. There are some particularly gray winters I think we all could benefit from a SAD light.

February 17, 2010 - 8:08pm


This is such an interesting post. I have battled depression and have wondered several times whether SAD could be a big part of it, as I always feel my best during the months when we have longer daylight hours and more sunshine overall. You answered all my questions, as well as some I didn't even know I had! (I would have never thought to wonder whether there was a skin cancer risk. But I'm glad to hear that it's the retina, not the skin, that reacts to the lights.) Thank you for a truly informative and thoughtful post.

February 17, 2010 - 9:53am

Thanks Pat, for adding that excellent link for others to read.

February 15, 2010 - 6:29pm
Expert HERWriter Guide Blogger

Great information, Michelle. The Skin Cancer Foundation also advises caution in the use of SAD lights, and warns against the use of tanning beds. According to the Foundation, new high-pressure sunlamps emit as much as 12 times the annual UVA dose compared to the dose people receive from sun exposure. Those who use tanning beds are 2.5 times more likely to develop squamous cell carcinoma and 1.5 times more likely to develop basal cell carcinoma.

February 15, 2010 - 5:21pm

You're welcome Susan. I think reputable lights would have filters in place but it is always a good idea to check. Glad SAD lights have helped you and yep, tanning beds are altogether a bad idea these days.

February 15, 2010 - 2:00pm
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We value and respect our HERWriters' experiences, but everyone is different. Many of our writers are speaking from personal experience, and what's worked for them may not work for you. Their articles are not a substitute for medical advice, although we hope you can gain knowledge from their insight.