I suggest that during a fast you avoid tea (camellia leaf) since the caffeine will have a stronger effect on you. Also it is normal to have trouble sleeping during a fast. You can instead drink rooibos tea from Africa (it is red). It has a naturally sweet taste, no caffeine and it helps people to sleep better. Here is a page with good deals on it (Rooibos Tea) since I think stores charge too much for herbal teas.