Is safe to alternate a nootropic like optimind in for vyvanse (lisdexamfetamine) on days that i don't have as much to get done or could it be dangerous to my health?

Not recommended: If you are being prescribed Vyvanse, (lisdexamfetamine) presumably for problems with attention, focus, and concentration, then it is important that you take it as instructed on a daily basis, irregardless of the amount of work you have to do. The purpose of taking a stimulant to address these symptoms is to enable you to function effectively in various domains of your life. Hope this helps. All the best.