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.
The average treatment time for invisalign is 12 months. The aligners provide .25mm of movement to the teeth per aligner. The more crowded your teeth are the more time it will take. The best way to insure that you are going to minimize your time in aligners is to wear them for 22+ hours a day and change into your next aligner every two weeks.