thats wrong. they really only grow vertically in the dark, and who knows what the roots do. ive read that lights of..its using stored energy (mainly to stretch to, look for lights) and during the day its building, and storing energy, more productively.I also have noticed more growth during lights out.
still, dont overwork them. theyre life. 20/4 at most
humans rebuilkd the best when where asleep. anyone that has read a plant anatomy book could you if plants are the same or not, im not positive. its not on surface literature.