Effect of low-caffeine green tea against sleep and stress in the middle-aged people - Sleep and stress in the middle age

We examined the effects of green tea with lowered caffeine content (LCGT) on stress and quality of sleep of middle-aged individuals (n=20) in a double-blind crossover design. Standard green tea (SGT) was used as the control. The level of salivary amylase activity (sAA), a stress marker, was significantly lower in participants that consumed LCGT than in those that consumed SGT. Sleep quality was higher in participants that consumed a larger quantity of LCGT. In addition, a self-diagnostic check for accumulated fatigue was significantly lower in those participants that consumed LCGT than SGT. These results indicate that LCGT intake can reduce stress in middle-aged individuals and improve their quality of sleep. The reduction in caffeine is suggested to be a valid reason for enhancing the anti-stress effect of green tea.