I live in a place where we do not have completely dark nights in the summer.
This is how my room looks like (picture from the web, just example - Sliding doors with vertical blinds).

I'm looking for an easy solution. And I do know that sleeping masks exist, I just hate them.
Possible solutions in my understanding:
- Tint attached directly to windows - then I do not have control during the day.
- Couple of blankets pinned in front of the blinds - looks ugly.
- Get new curtains - hard to install (expensive?)