Waking up with the sun...
Would this hold equally true when the summer nights are very short (sometimes not even existing at all in some places) and winter nights are very long?
I suspect that traditionally, people would sleep more in the winter, and less in the summer, but they still needed some sleep and some waking time...
Good point Viking, Up north there is so little night in summer that if you rose at sunrise, you would hardly sleep. It is skewed in that case I would say.
We should get about 6 hours sleep a night ideally, and time it so that we can awaken to see the sunrise.