But beware of excess

Too much caffeine can have the opposite effect. According to ANSES  (the French Agency for Food, Environmental and Occupational Health & Safety), approximately  30% of adults  and  11% of children  in France consume  more caffeine than the recommended dose , which can cause:
 palpitations and restlessness,
 anxiety and nervousness,
 sleep disturbances,
 and long-term cardiovascular and bone effects.

Some people are more sensitive to caffeine, including  pregnant women ,  children , or those taking  heart or anxiolytic medications .