Caffeine
Caffeine is one of the most common stimulants that can be found in many drinks like tea, soda, coffee, as well as energy drinks. It can help increase alertness and reduce fatigue by blocking certain receptors. Most adults could safely consume around 400 milligrams of caffeine on a daily basis, but some people can be extremely sensitive to the substance. This can be related to several genetic factors and a reduced capability of metabolizing and releasing caffeine. Typical symptoms include anxiety, rapid heartbeat, insomnia, jitters, restlessness, and nervousness.[8]
