My housemate always swears by this and says he always writes most of his guitar riffs/songs hungover. And I realised I tend to come up with more stuff when I'm hungover also, so I'm wondering if this is the case for everyone? Obviously I'm not talking the really bad hangovers, more the sort of tired and fatigued hangovers, I think it comes down to not really thinking about things as much so you sort of just do it and that way it just comes out.