Black tea is a type of tea made from leaves that have been allowed to wilt and fully oxidize: more than yellow, oolong, white and green teas. It is during the oxidation process, where oxygen comes into contact with the enzymes in the tea leaf, that distinguishes black teas from other teas.
During the oxidation process, also known as fermentation, the leaves turn darker as chlorophyll begins to break down and flavors and colors are released. Black teas are characterized by a deep rich color, full-bodied flavor, and contain more caffeine than other types of tea.
Black tea generally has a high concentration of caffeine, due to longer infusion time compared to green tea, along with higher steeping temperatures, typically boiling. Since black tea is oxidized, more caffeine is extracted from the leaf versus other teas. An average cup (8 oz) of black tea has 0.001 oz of caffeine but can contain as much as 0.003 oz.
Black tea has one of the highest caffeine levels of all teas due to its increased oxidation process. For a good night's sleep, we recommend reducing or stopping your intake of black tea at least 2-3 hours before bedtime.
A better alternative would be Matcha, Rooibos, or any other herbal tea. For increased focus, energy and attentiveness, the best time to drink black tea is in the morning.
Black tea has a variety of health benefits similar to that of green tea, especially for soothing an upset stomach. The polyphenols found in black tea may help maintain a healthy gut and treat diarrhea particularly.