If you sleep only in darkness hours, then winter would have you sleeping for a lot longer; then surely you'd be sleep deprived in summer.
I do need less sleep in the long summer days I feel but, the winter days are very short here.
Most animals will have a larger sleep at night, but general nap whenever the feeling strikes them.
I would think that after hunting and eating, a snooze would be common. Kind of like Christmas every day :)
I often wonder why Australians didn't take on the Mediterranean way of up for work early in the summer when it's still cool
Blame the English. In my town, they didn't even put verandas on the early houses... I think they were buried young.