Light at Night May Interfere With Breast Cancer Drug
Even dim light suppresses melatonin, which appears to make tumors resist treatment
By Elizabeth Armstrong Moore, Newser Staff
Posted Jul 30, 2014 8:52 AM CDT
Even the dim light from a nearby street lamp can impact melatonin levels, a study finds.   (AP Photo/Mahesh Kumar A.)

(Newser) – Light at night has already been widely linked to poorer sleep quality, but now even dim light is being shown to interfere with a breast cancer drug's ability to do its job. So says a new study on rats out of Tulane University School of Medicine, which found that even the low light of a nearby street lamp interferes with the body's natural production of the sleep hormone melatonin. And the rats (all of which had human breast tumors) exposed to dim light at night not only exhibited lower levels of melatonin but had larger, faster-growing tumors that were also completely resistant to the breast cancer drug Tamoxifen.

"Our levels of melatonin are not determined by sleep, as many people think," one researcher tells Medical News Today. "It is actually the darkness that is important." And he tells the BBC that the blue light emitted from digital devices such as TVs and tablets is particularly disruptive for melatonin production. Other studies have suggested that melatonin may help improve cancer treatments. Still, researchers warn that this study needs to be replicated and validated in humans before determining that all the same mechanisms are at play. (City lights have also been linked to higher breast cancer rates.)

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Showing 3 of 12 comments
Ezekiel 25:17
Jul 30, 2014 11:58 PM CDT
I used to sleep in a big empty home that my grandparents owned. I could have picked any number of bedrooms to sleep but I wound up picking the center den. That's because the alarm panel was in that room and I set the alarm for peripheral sensor mode. I was afraid of not being aware of a break in. But I usually wound up going to sleep with the tv on. The problem with that is when the program that is on gets into your dreams. I can remember numerous times I had dreams where the plot line of the movie was the dream I was having. But straw that broke the proverbial camel's back was when I left it on a channel that had a televangelist that came on. You know, it was the guy who asks you to join his millionaire club by sending him $1000. Well, he's the millionaire. So I'm cold asleep and all of the sudden the subliminal messages start to soak into my mind. Next thing is I'm half awake when he points to me and says I must do it or God cannot bless me. I actually was in a state of depression the next day and that ended my late night tv.
baldpirate
Jul 30, 2014 10:04 AM CDT
This Just In: Lighting Bugs May Interfere With Cancer Drugs Oh, the absurdity ! ! !
Who_Cares
Jul 30, 2014 9:58 AM CDT
I have to take ZZZQuil and Melatonin so I can fall in sleep. In my bedroom is pitch dark, can't see a thing. Couple of times I hit the wall and almost broke my toes, couple of times I almost took down the dresser with the Plasma TV on it but I can't fall in sleep if there is a light around. Sometime the light from fire ditector drives me mad or light from my clock, that I have to cover. I can't imagine how some of my neighbors can sleep with the lights on in the house.