After about 4-6 days you'll get what we call "the dreams"
At the time you'll shit yourself and dread going asleep after the first time you have one, but you'll look back and laugh your tits off at some of the stuff you dreamt of.
I used to bang out tunes in one day no dramas, however now ill start a tune and get 60% of the ground work down then visit it back over a week or two untill im really happy - then change it some more to surprise myself.
and i can work both in days and nights - but ive gotta be in that "zen-like ...