Any thing that can help me awake?

I am feeling really tired these days although only in my 27 weeks of pregnancy. Everyone who sees me would be surprise at how big I look now, and not only that, I feel physically and mentally worn out as well. Now I spend most of my time on bed, hoping to take some weight off my pelvic area during sitting or standing. I doubt there is anyway that can makes me feel any better. Although I still take prenatal vitamins, I still prefer the natural way. Must really check out with the herb expert or shop at iamshaman.com to see what is available for pregnant mums like me to keep me fresh and awake for a longer time.