It is an interesting point, what do you do if you live very far north (or south) and the length of the day varies widely? (I always sort of suspected human beings were never meant to live in Scotland!) This summer we've been away a lot, and when we're home, my husband now finds it impossible to sleep past about 5AM because there's too much daylight - and it does NOT improve his disposition any!

BTW I just have to say I love the cavepeople forum. Over on the Atkins board everyone always seems to want to talk about cheating, or why they're not losing weight fast enough, or the latest weird chemicals. I think I like the conversation here a lot better!