I love to roam the open world of Witcher, and can't help noticing lots of game time is passing away while doing so. Day and night, over and over.

So far I did not notice any possible influence it might have on quests (neither the main quest, nor any side quest) however I have a feeling I might miss (or already missed) some things available only if I act quickly and finish things in a certain time range.

Can anyone tell for sure if there is any meaning, or side effects, to the passing days?