Bright nights kindle cancers in mice

Data from mice subjected to constant illumination suggest that artificial light may increase risks of lung and liver cancers and leukemia.

Exposure to light at night reduces production of melatonin, a hormone that calibrates the body’s biological clock and its secretion of estrogen (SN: 10/17/98, p. 248: http://new.sciencenews.org/pages/sn_arc98/10_17_98/19981017fob.asp).