Excellent article Eric. It's a wonderful feeling to be in the 'creative flow' with the accompanying feelings of being fully present to one's work, whilst being connected to something other than the usual (chattering monkey) mind.
Sound sleep is so important for the 'creative.' As are all the other requirements of our physical body to be at its best. As you say, we need to be able to determine what works best for us, at any particular stage of our life. And this can take many years of experiential learning.
I find that the feeling of physical well being, overflows to my emotional and mental wellbeing ~ And then I can allow for the 'something else' to support my work. 🙏 🌀 🙏