There are a lot of claims for a lot of tisanes, but scientific studies
to back the claims are sometimes sparse. I'd suggest drinking your tea
plain (green or black) throughout the morning and early afternoon, and
your ginger tea in the late afternoon and evening, so you won't have
caffeine interfering with your sleep. Ginger tisanes often come in a
mixture with other spices and herbs- licorice, black pepper,
peppermint.... Toci