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I’ve mentioned before on this list that there is
increasing evidence that exposure to light-at-night increases the risk of
cancer. The mechanism is apparently that light into the eye affects the pineal
gland and causes it to suppress production of melatonin. Melatonin not only
makes you feel sleepy, but also suppresses cancer growth. A new study by a Japanese researcher of junior high school
students studying between the hours of 9:30 and 11:30 pm found that those
studying under bright fluorescent lights had suppressed melatonin levels
compared to those in a typical dimly lit Japanese home. The research paper can
be found here: http://www.nelsonbay.com/~gc/Journal%20of%20Circadian%20Rhythms%202004-2-4.pdf A summary of research in June last year is found here: http://www.nelsonbay.com/~gc/LightingForHumanHealth-June2003.pdf Dr Pauley is the chair of a task group investigating the
mechanism. In a recent Internet exchange with me, Dr Pauley stated: “All visible light
wavelengths will eventually lower MLT . Blue emissions do this faster
than light shifted toward the orange and red mainly because the population of
the few retinal ganglion cells that have melanopsin absorb blue light and
trigger a circadian response = the signal to the clock center in the
hypothalamus. That in turn tells the pineal gland to reduce its production of
MLT. This does not happen in darkness. MLT suppression takes much longer with
incandescent light and it takes hours for red light suppression.” This is interesting, because we have had a campaign
by our electricity authority to exchange incandescent lights with fluorescent
ones in the name of reducing energy consumption. However, this shift may well
increase the likelihood of cancer. - Greg |
