Some references, a synopsis, and a small associated piece in a box -- all on the possible importance of full darkness each night for avoiding malignancies can be found in Science News Vol. 154, No. 16, October 17, 1998, pages 248-250. Worth seeing if these can still be found at the website http://www.sciserv.org, or if a reference librarian can get a copy for you. [Posted in FML issue 3027]