Caffeine can make people jittery and cause fast and sometimes anbormal heart rhythms. It sounds like you should stay away from caffeine. Reasons to seek a doctor would be if you are having passing out or near passing out episodes, palpitations, or if there's a history of young people dying suddenly in your family.
The total duration of treatment depends on the complexity of the treatment and is generally comparable to that of traditional braces. Typically treatment can last between 9 and 18 months. During your consultation, your Invisalign Provider can provide you with more detailed information.
You will wear a set of Invisalign trays for two weeks at a time. Each tray is manufactured so that the teeth are slightly straighter than the previous tray. The teeth will typically move 1/10mm per tray. So when you put a new tray in, the teeth in the tray are slightly straighter than your teeth are.