Circadiana- Everything You Always Wanted To Know About Sleep (But Were Too Afraid To Ask) – via this MeFi thread.
“There is a continuum of individual sleep patterns ranging from extreme “larks” who fall asleep at the first inkling of dusk but wake up before dawn, all the way to the extreme “owls” who stay up quite late and wake up once the day is in full swing, and of course everything in between. No matter where you are on this continuum, you tend to sleep more during the winter long nights than during the short summer nights.” – quote in context