The best loose leaf tea for sleep and relaxation is low in caffeine. All true tea, Camellia sinensis, contains caffeine so you may want to select a herbal infusion (which are all caffeine-free "tea").
Our Soothe Me tea is blended from herbs specifically to calm and aid sleep. For a loose leaf nighttime tea you might want to try a blend that only contains a little tea with herbs like our Recovery Tea.
If it has to be pure tea - we recommend trying a later infusion. As you reinfuse the best loose leaf tea, you not only reveal hidden subtleties of flavour but also dissolve some of the caffeine. So the second, third or even sixth infusion has less caffeine left in the loose leaf making a better sleep tea. A Gyokuro is ideal for this.