How do people who live in different parts of the world vary in terms of sleeping?

When I learned that melatonin was released in the presence of darkness I wondered what sleep patterns were like in different places of the world, where the sun doesn't set until late at night. Typically thinking of Alaska. What I came to realize after looking online was that there isn't a difference in sleeping patterns. The sun usually sets around 10pm in Alaska and households will have blackout shades to restrict light from coming in which then will produce melatonin to run throughout your bodies system. I couldn't find too much on this topic but I guess that's because it was kind of an unusual question.