"What effect does coffee have on sleep?"

Translation: Hvilken virkning har kaffe på søvn?

[Elgtrener]

Virkning = effekt?

[deactivated user]

Why is the English sentence not : What kind of effect... Seeing as it's 'Hva slags...'?

[Mafuljica]

Could it be translated like this:
"Hva er kaffes virkning på søvn"

[Alathat]

In English, there is a distinct difference in meaning between "which effect (of a given set already discussed or known from context)" or "what effect (any answer is possible - especially one the person asking the question may not have thought of or be aware of)". Does this distinction not exist in Norwegian?

[fveldig]

There is not really any distinction unless specified in this case ("Hvilken/Hvilket/Hvilke av de nevnte" = "Which of the mentioned"), or it may be understood by context.