Dear Engin,

To drift, as in driftwood, ist to be carried by some current, for instance of water or air. In your quotation it means moving passively or aimlessly or involuntarily; it could be into sleep, but not necessarily. The exact meaning seems to be in what God expresses three lines further down: "Absolutely, take those moments of reverie and let your heart and mind go where they will."

Does that give a clearer picture?

Have a wonderful day, and thank you once again for the great work you are doing!
Jochen