University Heights, OH (PRWEB) October 16, 2012
For more than 20 years scientists have been warning that exposing the eyes to light at night increases the incidence of cancer. The mechanism is thought to be the reduction in the amount of melatonin being produced. When the eyes are exposed to light at night the flow of melatonin is delayed and reduced (3). How much depends on the color and intensity of the light. The blue rays in ordinary white light are most effective in reducing melatonin flow (4). Wearing amber glasses that block blue light will restore the flow (2).
Experience since 2005 by thousands of customers of Photonic Developments LLC that operates http://www.lowbluelights.com has shown that putting on their amber glasses for 2 or 3 hours before bedtime gets the flow of melatonin started so there is plenty present in the bloodstream at bedtime. Customers report that sleep comes quickly and deeply.
Use of the amber glasses that block blue light may be of value to nurses working night or rotating shifts. Permanent night shift workers should try to turn their days into nights with blackout shades according to Richard Hansler PhD, author of “Heroes of Cancer Prevention Research” (Amazon). He further states, “They should put on the glasses 2 or 3 hours before going to bed in darkness during the day. They should keep the same schedule on days off and weekends. This should maximize their production of melatonin and thus avoid any increased risk of breast cancer”.
His advice for rotating shift workers on slowly rotating shifts (e.g. monthly) is to try to adapt as the shifts rotate and try to use the glasses 2 or 3 hours ahead of bedtime regardless which shift they are on. Again, they should sleep in darkness.
For quickly rotating shift workers (a week or less) it may be possible to keep their body on the same schedule as when they are working days. That is, put on the glasses at the same time every evening (e.g. 8 P.M.) whether planning to go to bed at 11:00 or on the nights they are working. Wear them until bedtime on days off or all night while working (e.g. until 7 A.M.). Since melatonin will be present when they are at work, sleepiness is potentially a problem, according to Hansler. One brief study (2) found no decline in performance under these conditions, i.e. while wearing amber glasses while working at night.
The problem of increased risk of cancer is not restricted to shift workers. Virtually all people living where electricity is available are experiencing reduced time in darkness compared to the time before artificial light. This very likely increases the incidence of cancer especially breast cancer and prostate cancer due to reduced melatonin. Blind women make melatonin for 11-12 hours a night. They have about half the incidence of breast cancer as women with normal vision (5). People with normal vision but kept in darkness make melatonin for the same 11-12 hours, on average. Wearing amber glasses for a few hours before bedtime combined with 8 hours in darkness while sleeping will restore normal melatonin production to that enjoyed while humans evolved.
For those who do not like wearing glasses, light bulbs that do not produce the damaging blue rays are available at http://www.lowbluelights.com , along with filters for electronic devices with glowing screens.
(1) Eur J Cancer. 2012 Jul;48(11):1722-9. Epub 2011 Aug 16.
Case-control study of shift-work and breast cancer risk in Danish nurses: impact of shift systems.
Hansen J, Stevens RG.
(2) J Clin Endocrinol Metab. 2005 May;90(5):2755-61. Epub 2005 Feb 15 Links
Blocking low-wavelength light prevents nocturnal melatonin suppression with no adverse effect on performance during simulated shift work.
Kayumov L, Casper RF, Hawa RJ, Pereelman B. Chang SA, Solalsky S, Shapiro CM
(3) J Clin Endocrinol Metab. 2011 Mar;96(3):E463-72. Epub 2010 Dec 30.
Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans.
Gooley JJ, Chamberlain K, Smith KA, Khalsa SB, Rajaratnam SM, Van Reen E, Zeitzer JM, Czeisler CA,Lockley SW.
(4) J Neurosci. 2001 Aug 15;21(16):6405-12.
Action spectrum for melatonin regulation in humans: evidence for a novel
Brainard GC, Hanifin JP, Greeson JM, Byrne B, Glickman G, Gerner E, Rollag MD.
(5) Cancer Causes Control. 2009 Nov;20(9):1753-6. Epub 2009 Aug 1.
Total visual blindness is protective against breast cancer.
Flynn-Evans EE, Stevens RG, Tabandeh H, Schernhammer ES, Lockley SW.