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]