Invisibility Spell

A question arises during our DW PBF
can a Wizard mantain active Invisibility (or any other spell) if he's sleeping?

I know that tecnically sleeping is not in the list of the events that end the spell, but perhaps Magic in DW requires constant concentration and a sleeping wizard cannot concentrate on the spell.

I'd ask the wizard how he keeps the spell up in his sleep. Then I'd tell him the cost or consequences and ask...

ask the player, he's the only one who truly know how his magic works. Also, I don't think that there's anything wrong with sleeping while invisible.

Not until the Fighter gets up to piss and forgets where the wizard is sleeping.

Yeah, I don't think there's a by-the-book answer. I think it's up to your group to decide. Either ask a player or go off what your table has already established: given how magic has worked so far in the campaign, does it make sense that the spell would remain?

Does a wizard actually sleep invisible when no-one sees him lay his head down to rest?