Can confirm the sun plays a huge role in sleep cycles. I live in Alaska and during the summer when we get about four hours of twilight I am awake all the time and live on basically four hours of sleep without any repercussions of feeling tired. On the opposite side, in the winter when we get maybe four hours of daylight I become like the bear and basically hibernate. Can’t drag myself out of bed to the point I make a four shot esspresso before bed and put in a bedside thermos and drink it (after water) a half hour before I have to actually get out of bed. Still wouldn’t live anywhere else - lots of views for days and too much fun and fish here!