while vitamin's do help and are a good idea if you are having problems with not having enough energy all the time you should talk to your dr you could be having problems with specific vitamin deficiency's or it could be something more serious, like how long and well you sleep, could be a thyroid problem a sleeping disorder
If you're an adult, you definitely want to take a very potent multivitamin. For women, it's been proven that prenatal vitamins are excellent for giving energy-even if you're not pregnant. For women they will need iron. For men, take lots of B12.