Studying is when I fall asleep is an example of =>2.parallel structure.
Why? "Studying is..." can be completed in one way,let us call it (a 1,a2,...)
(a1) ...the elementary precondition for getting any kind of a graduation."
(a2) not just the action of opening a book and staring at the lines,it takes much more.
"When I fall asleep" can be completed is different ways,let us call them (b1,2...)
(b1) ...is an example of a very special situation which I am are in,
seen under the aspect of physiological processes in my body.
(b2) ...is an example of an uncompleted sentence which causes irritation of
your dialogue partner.