This sentence is taken from a Norwegian poem by the same name, written by Arnulf Øverland.
The poem, which was written in 1936, warns about the rise of nazism and fascism in Europe, and is a chilling prediction of what we know was to come.
(The video linked above contains some rather strong imagery from WWII. Plain text version.)
Note that "må" in Norwegian has a different meaning than in Danish. It means "must", rather than "may". The sentence above is ambiguous in the sense that it is not clear what the "ikke" refers to, the verb "må" or the verb "sove", i.e. whether it is necessary that you not sleep or not necessary that you sleep.