Two common causes of fatigue in women that I can think of right off hand are anemia (as the first responder posted) and thyroid problems. My sister-in-law tried the natural approach to dealing with her hypothyroidism, which caused her extreme fatigue, but finally gave in to taking medicine and going on a gluten-free diet. She is back to her old self.
If neither of these areas are a problem for you - a good quality, potent B-Complex is known to give energy and reduce stress. In fact, they don't advise you to take it at night. I buy mine at the local health food store. I deal with my borderline-anemic tendencies by cutting out the chai (tea affects iron absorption) and taking vitamin C along with oatmeal and black-strap molasses (enhances absorption of iron). Going caffeine free also helped me with dips in energy - although it takes about a week for your body to adjust.
A third reason for grogginess is a failure to wake up and go to bed at the same time every day. Our bodies prefer a routine sleep schedule.