Exposure to light at night, which shuts off nighttime production of the hormone melatonin, renders breast cancer completely resistant to tamoxifen, a widely used breast cancer drug, says a new study. Melatonin by itself delayed the formation of tumors and significantly slowed their growth, researchers report, but tamoxifen caused a dramatic regression of tumors in animals with either high nighttime levels of melatonin during complete darkness or those receiving melatonin supplementation during dim light at night exposure.
These findings have potentially enormous implications for women being treated with tamoxifen and also regularly exposed to light at night due to sleep problems, working night shifts or exposed to light from computer and TV screens. "High melatonin levels at night put breast cancer cells to 'sleep' by turning off key growth mechanisms. These cells are vulnerable to tamoxifen. But when the lights are on and melatonin is suppressed, breast cancer cells 'wake up' and ignore tamoxifen," Blask says. [emphasis mine]
"Melatonin by itself delayed the formation of tumors." I'm so glad I've been using 2.5 mg of sublingual melatonin before bed.
Sounds like your melatonin supplement has been helping more than you knew, Ruth... glad to hear it!
I imagine it'd be difficult to achieve complete-enough darkness in the bedroom, even with good light-blocking window shades, if you have an alarm clock, phone charger, air cleaner, etc.
GC, if I read correctly, it's ok to have dim light. LED lights on the clock or phone charger are probably too insignificant to worry about. Maybe I didn't read right.
Let me look again...
Dim light suppressed the naturally elevated melatonin levels that occurred in total darkness; but melatonin supplements overcame that.
(I do remember reading an article a few years ago about small LED lights being significant.)