This is a graphic representation of the hours of darkness in Reykjavík, Iceland.
The months are represented across the bottom (Jan = I, Dec = XII)
Now in June (VI) there are no hours of darkness. You could golf all night.
Many find it difficult to fall asleep during the night when the sun is shining. In general, visitors and newcomers are most affected. Some natives are also affected, but in general to a lesser degree….
Wikipedia – Midnight sun
I’ve hiked in Alaska, Yukon and Patagonia during long days, but it’s never been this bright at night.
Weird.
besthike.com 
As a person who lives for as much daylight as possible, summer months in Iceland would be welcome. In Calgary, Alberta, Canada the window for long days in the mountains is limited but less severe than the far north. There is a case for having separate dwellings in each hemisphere. Looking forward, with a fair degree of envy, to your posts on Iceland adventure. Happy trails and stay safe.