I'm with you Tom. The effect of light and day length is not trivial. The discussion on paleolithic eating seems to be lacking because little has been said about the profound post-Edison extension of day length and worldwide. incursion of articial lighting. Light and day length are basic to all life processes, certainly more basic than diet... It is alarming to me how dark star lit skies are fast disappearing.
The best documented research I have seen on the subject is in "Lights Out" http://www.amazon.com/exec/obidos/ASIN/0671038680/qid=1021053051/sr=8-1/ref=sr_8_71_1/104-9452942-6421524
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Mike Lillie