SEATTLE, WASHINGTON. Several studies have found a correlation between low nighttime melatonin levels and the risk of breast cancer. It is believed that low melatonin levels stimulate the pineal gland to call for the production of more estrogen, a significant risk factor for breast cancer. Researchers at the Fred Hutchinson Cancer Research Institute now report that nighttime exposure to electromagnetic fields commonly found in the home (60 Hz) can suppress melatonin production. The study involved 200 women aged 20 to 74 years with no history of breast cancer. The women participated in two 72-hour trials over a span of 6 to 12 months (to include the variable of seasonal change in the number of hours of darkness). The researchers measured the levels of light and electromagnetic radiation in the women's bedrooms during the night, tested urine samples for the level of 6-sulfatoxymelatonin (the major metabolite of melatonin), and conducted interviews to determine alcohol usage, smoking status and use of medications.
The researchers conclude that exposure to higher magnetic fields during the night is associated with a
significant decrease in melatonin production. Melatonin production was also highly dependent on the
number of hours of darkness (the more dark hours the more melatonin is produced). Increasing age and
alcohol consumption was also associated with reduced melatonin production as was the use of certain
classes of medications (beta-blockers, calcium channel blockers and psychotropics). NOTE: This study was
partially funded by the Electric Power Research Institute.