Lemon Verbena is a very popular drink in both Spain and France. Where it is drunk hot or cold. It is a natural sedative as well as a digestive tonic. The tea is also generally considered good for soothing bronchial and nasal congestion.
Lemon Verbena is a tropical plant, Aloysia citrodora syn. Lippia citriodora, there is an English Verbena whose common name is Vervain. Also Available as Coarse Cut
It is delightful combined with whole leaf mint and left in the fridge in cold-water overnight and then garnished with strawberries and slices of orange. For a hot tisane I would use boiling water and seep for at least four minutes adjusting for personal taste.
It goes without saying that if you're pregnant (or are under the doc for anything) caution should be exercised with herbal decoctions.