Fascinating topic.

I especially enjoyed reading the article posted by Caveman.
The bit about segmented sleep makes a lot of sense to me. I've noticed that sometimes I will nod off during the 10 o'clock news, sleep for several hours and then awaken shortly after midnight feeling quite awake. I read for about an hour and then feel quite sleepy again.

We just turned the clocks back last night. Lately I have been feeling the urge to go to bed earlier but have ignored it so far. After reading this thread, I think I will begin going to bed at 9 pm. I usually have to be up by 5 am so this still leaves me in a bit of a sleep deficit according to the recommended 9.5 hrs. Most days I can probably fit in a short siesta after lunch so this might help a bit.

BTW, I have a thin friend who has always said getting lots of sleep is key to maintaining her weight.