Caffeine, found in coffee, tea, energy drinks, cola, and some medicines, stimulates the nervous system. In people prone to anxiety it can heighten symptoms such as a racing heart, restlessness, jitteriness, and even trigger panic-like feelings. The amount that causes problems varies a lot between individuals, and some people are far more sensitive than others.
Caffeine also interferes with sleep. It blocks the brain chemical that builds up sleep pressure during the day, and it stays in the body for several hours, with effects often lasting six hours or more. Drinking it in the afternoon or evening can make it harder to fall asleep and reduce the quality of your sleep, even if you do not feel wide awake.
If you struggle with anxiety or insomnia, try reducing your total intake and avoiding caffeine from early afternoon onwards. Cut back gradually to avoid withdrawal headaches. If symptoms persist despite this, or you rely on caffeine to function, talk to a doctor, as underlying anxiety or a sleep disorder may need attention.