I drink black tea in the morning and coffee at noon to afternoon. When I started drinking my tea out of a can, so round about 3 cups instead of 1-2, i noticed t

I drink black tea in the morning and coffee at noon to afternoon. When I started drinking my tea out of a can, so round about 3 cups instead of 1-2, i noticed that my heart rate would sometimes mess up somehow (happens with too much coffee too). The caffeine (or teeine..) amounts in tea are comparable to coffee (~between 1/4 and 1:1), so in the end it stands to reason that tea (black, green, white, yellow) can have a very similar effect as coffee.