The Ability of Green Tea With Lowered Caffeine to Reduce Stress and Improve Sleep

Abstract

Abstract Green tea is the most popular beverage in Japan and Asian countries. Theanine, the major amino acid in green tea, has a significant antistress effect on animals and humans. However, this effect is blocked by caffeine and gallate-type catechins [e.g., epigallocatechin gallate (EGCG)], two other main components of tea. Caffeine is also known to affect sleep. We made green tea with a lowered caffeine content, low-caffeine green tea (LCGT), in which elution temperature was set at low temperature to suppress the elution of EGCG. The antistress effect of each component in LCGT indicates that theanine, arginine (Arg), and epigallocatechin (EGC) cooperatively suppress the counter-effect of EGCG and caffeine in mice. The level of salivary α-amylase activity, which is a stress marker, is significantly lowered and some sleep parameters are improved after the ingestion of LCGT by humans. The daily ingestion of LCGT is suggested to be a useful way to improve daily problems caused by stress, as well as sleep, ranging from young to elderly people.