Finland how do you sleep without window-blinds?

First at all, I were really surprised when I arrived here because I am get use to have blinds in windows to cover the sun. In Spain we have a lot sun so it is really important to have cover in windows so you are able to sleep properly. However, when I arrived here my surprised was huge due to the fact that they don´t use blinds! So in the first days I wasn´t able to sleep well.

There are no blinds in Finland. As much there are curtains that block the direct light, but it is not possible to block it all to have a great night of sleep as it happens in Spain.

Finnish people in particular, and the Nordic and Scandinavian countries in general, so accustomed to extreme changes in light, this does not affect them. In winter, if you are further north of the Arctic Circle, there is no light during the day, but the Kaamos, the polar night. If you are further south, there are only a few hours of light.
In Summer there is either the aforementioned white night under the polar circle or the midnight sun over it.

On the other hand, to those of us from southern Europe, this is a change. Neither rests so much, nor so well. And the only solution apart from installing the blinds, of course is to put on a sleeping mask.