The timing of caffeine, if you choose to use it, is carefully planned to help you stay awake at the right time and see light while having minimal impact on sleep. 

Sometimes, a short nap is indicated in the day when caffeine is also scheduled at times when we expect you to be tired. The caffeine will likely not have much impact on your short nap but if you wish, feel free to stop caffeine 2-3 hours before the planned nap. If you cannot nap, continue taking caffeine as indicated.

Learn more about caffeine when traveling here.