I was at a wedding in Sweden near midsummer with a lot of international guests. They were quite surprised to get out of the reception dinner at 10pm and see that the sun was still up. We were below the arctic circle, so no midnight sun, but it doesn't really get dark during the night, you get an hour or two of twilight, and then the sun rises at 2am again.
I travelled to Stockholm from North America a few decades ago, right around midummer. Worst jetlag of my life.
The problem was that 20 hours of daylight, especially having 2:30 AM feel like 6:30AM. It was impossible to get an adequate amount of sleep. The paper thin curtains in the cheap hotel where I stayed did nothing to block out the light.
If I am ever in that part of the world at that time of year again, I will be bringing a sleep mask and seeking out a hotel with proper blackout blinds or curtains.
You can just bring or buy some pop-up travel blackout blinds made for babies. We used those with great effect when visiting my parents' summer house in Northern Norway in the summers when the kids were young.
Bonus, they now work as great blackouts in my home office for video calls when I do not want sunshine and clouds to change my green-screen effects etc.
I would have thought that for places that close to the arctic circle would be a national crime to not have full black out curtains. The difference being the punishment based on what nation the crime was committed.
I live in the south of England and experienced this in Scotland. I was trying to get somewhere to pitch my tent but rapidly running out of light, or so I thought. It was the height of summer and it just never really got dark. Maybe England isn't as different as I think it is, but it was strange to find my assumption that night=dark was quite wrong.
