Switching from 24hrs. to 18/6?

I have my mothers under 400w MH 24hrs. I was thinking of moving them to 18/6 to reduce stress, save electric, etc...
My question is should I be concerned about making the move? I don't want them to flower,herm, or stress.

no you should be good plants need sleep aswell

maybe should let it rest without light for 24 hours..befo u make the change..just to be sure it doesnt shock them...